CA2057929A1 - Method for recovering breaker metal cord threads from tire - Google Patents

Abstract

Abstract A method involves heating metal cord threads and separating metal cord threads from rubber.
Output is increased and power consumption of the process is lowered by preliminarily completely cutting through a tire in such a manner as to expose the ends of metal cord threads and by heating these threads to a temperature of complete thermooxidation destruction of rubber layers adjacent to these metal cord threads.

Description

20S792~

~ETHOD FOR RECOVERIN6 BRE~KER METAL CnRD TUREADS
- ' ~ROM TIRES
Field of the Inventio~
5The,invention relates to processing of worn or re~ected rubber ' articles, and more spec~fically~,it, deals with methods for recovering metal tord th/n'éads from tires. The invention may be used at regeneration ~nd tire retreading plants 10and at rubber manufacturing plants~.
State o,~ the Art Known in the art is a method for recovering breakér metal cord threads from tires involviny heating metal cord threads ln a hlgh-frequency lS ' electromagnetic field and separating the threads from rubber tSU~ ~ 7~1S0). The metal reinforcement 15 heated in the electromagnetic fi,eld until its surface in contact with ruboer : reaches a preset temper~ture at which the nearest rubber layers are fu~ed~ and the reinforc'ement i 5 ' removed.
The dlsadvantage o~ this method resides in a low output because of a' compl1cated operation of ~eparat~on of metal reinforcement (metal cord ~5 threads of the breaker) from rubber since viscous cohesion between the cord threads and the fused surface of the nearest rubber ~ayers has to be overcome.
This state of the art method -is also def~cient because liquid viscous compon~nts of .

fused rubber (rubber oils) ~re present on both metal cord an,~ rubber liberated from the. cord which impalr utility propertles of the material during further processing of rubber and metal cord. 80th manual and~mechanized processing of rubber are complicated ~ithout the removal of these component~. .
This method also requires much energy 5i nce - heating of metal reinforcement i5 carried o~t without air.access~ and energy for aetivating thermal destruction amounts to 270 to 290 kJ/mol.
5ummary of the Invention ; The invention is based on the problem of providing a method for recovering breaker metal lS ~ord from rubber t~res i~ whlch an autocatalytic . heating and destruction are ensured by chanqing .
the heat~ng temperature and carrying out the ; heating in the presence of air oxygen -for thrmooxidation destruction! the rubber layers neare~t to breaker metal cord threads being pulverized without formation of oi 15 SO as to increase output~ lower power requirements and enhance utility properties of rubber.
This problem i5 solved by the ~act that ln a .method for recovering .brea~er metal cord threads from rubber tires~ comprising heating breaker metal c~rd threads in a high-frequency - electromagnetic field ~and sepRrating them from .

20~792~

rubber~ ~ccording to .the invention, a tire i5 completely cut through the breaker before the heating in a plane drawn per-pendicularly with respect to its axis of rotation in such a manner as to expose the ends of all metal cord threads~
; the heating o.f the ~ords being carried out to a temperature of complete thermoo~idation ~o~.t.r~ic~ o~ ruhb-ar ~.y~e: n~;~r~it to the metal cord threads.
Cutting a tire completely through the breaker - to expose the ends af all metal cord threads thereof to ensure oxygen access to these en~s and ; to rubber layers adjacent thereto with subsequent heating of breaker netal cord thread~ to a temperature of . camplete .thermoo:sidation destruction (this temperature here neans the - temperature at which co~plete thermal decomposition of rubber occurs int~ technic~l carbon and a hydrocarbon gaseo~s product) allow rubber layers adjacent to metal cord threads to be pulverize.d 50 a~ to rule out formation of a liquid fraction~ The breaker metal cord i5 th~s automatically separated from the tread and carcass of the tire. This greatly ~acilitates removal o~
breaker metal cord threads and enhances output.
It should be also jloted th~t the presence of a~r oxygen ~n the heating zone ensures the autocatalytic mode of thermal destruction of .

2~7929 rubber with an ene~.gy of - activation of th,ermooxidation destruction amounting to 150 to 190 kJ~mol., whereas a si~ilar process wlthout air access ~state of the art method) requires 27~ to S 290 kJ/mol. Power requirements are thus m-Ach lower.
In addition~ owing to the cDmplete thermooxidatlon destruction of rubber layers ad~acent to br~aker metal cord threads the inner ~0 surface~; of the tread and carcass rub~er remain dry so as to sL~bstantially enhance ut.ility properties of these rubber pieces ~nd rule out additional handling o~ these s~rfa~e during further procesing.
To. ~aci 1 itate processing and removal ~f breaker .metal cord threads~ the complete cutting of tires may be carrie~ out thraugh both lon~ltudinal borders of these threads. This cutting t,hrough the tire allaws a ring with the breaker to be formed. The two side walls thus separated from the tire~ which do not have breaker and which are of a subs~ntially planar configuration, facilitate ~tillzation as ring spacers and for blanking new parts.
. 25 To increase output~ a ring having the breaker is cut in a plane drawn through the axis of rotatlon to forn a strip. This allows the ~ost simple zone-type ~low-line ~eth~d of processing.

20~7929 ln~ addition~ the planar çtrip-like shape of the tread and carcass p~rts (after separation from metal cord threads) is~ the most suitable for processing to enhance productivity in blanking ! 5 rubber articles~and intermediate products.
It is pr~ferred~ in the ~ethod according to the invention, that in heating the;exposed ends of breaker metal cord threads an .o:<ygen mediu~ be provided by supplying o:~ygen so as to $ubstantially lower power requirements because in this case an energy of activation of thermooxidation destruction of rubber is as low as 80 to 110 kJ/mol. In addition~ this accelerates thermal destruction and enhances output.
lS Brief Des~ription of the Drawings The invention will now be described in detail with reference to the accompanying drawings il~ustratlng a method for recovering breaker metal cord threads from rubber tiresl in which:
Fig. 1 is a view of the working part of a tire with exposed metal cord (the tread is n~t 5hown);
Fig. 2 is a view of a ring with a breaker in a section taken along line II-II in Fig. 1~-with 2S tread;
Flg. 3 schematically shows a developed strip with a oreaker;

Flg. 4 is a ~ront eievation of an apparatus for cutting a t~e;
Fig. ! 5 is~ditto~ a plan view;
Fig. 6 is a schema~ic view of an apparatus S for heating a strip with a brea~e.r.
Preferred Em~atiment o~ the Inventi~n Fi~. 1 shows a tire l being processed having a breaker 2 which has two plies ~f metal c~rd threads 3 and a line 4 along which tire 1 is cut, ~ut-o~f ends of breaker metal ~ord threa~s 3, and two side walls 6.
Fig. 2 shows expased ends 7 of breaker metal eor~ threads 3 and rubber layer 5 8 nearest to threads 3.
lS ln addition, a ring ~ .formed after the : cutting of tire 1 is shown which has a tread ~0 ~nd a carcass ll as well a5 breaker 2~ Fig. 3 also show~ a strip 12 obtained after cutting ring 9.
Figs ~ and ~ show an apparatus fcr cutting tire 1 which comprises a driven pres~ure roll 13 and an idle pressure ~oll 1~ and a pair o4 clrcular knives 15 ~c~nly one is shown) with a drive 16. Line 4 along which the tire is cut i5 also.shown in Figs 4, 5.
Fig. 6 schematically shows an apparatus 17 for heating the strip with the breaker, comprising - a trough-like cAsing 18~. a pair o~ pressure rolls having a driven roll 1l and an idle roll ~0, an , ,-., .

inductor 21 of a high-fjrequenc~ generator (not çhown)~ an outlet nozzle ?2 for oxygen supply from a bottle 23~ as well 85 tread 10~ carcass 11 and metal cord threads 3 wh~ch are connected to one S another.
~ method far recovering breaker metal oord threads ~rom a tire is carried out in the ~ollowin~ manner.
: Rubber tire 1 tFigs. 1~ 4 and 5) i5 placed on drlven press~re roll 13 and is pressed against it by means of idle press~lre roll'14. Two circular knives 15 coupled to drive 1~ are then used ~or completely cutting through tire 1 along a local p~rtion of tire 1. Driven roll 13 is then ~sed for rotating the tire whereby complete cutting through tire 1 i5 carried oL~t along a plane drawn perpendicularly with respect to its axi~ of rotation along both borders of metal cord threads o~ breaker 2 ~along lines 5) ~Fig. 1)~ and their ends 7 are exposed. ~s a re~ult of the above outting-through operaticn ring 9 is formed ~Fig.
2) with breaker Z and al50 a pair- of side walls b ~Fig. 1~. It will be apparent to those skilled in the art that dia~eter ,of the ciroular knives~
their rotation speed a~d the speed of cutting through the tire~ as we-il as the width o~ a ring with the breaker depend on the size of the tire being handled.

20~7929 To facilitate processing and recovery of metal cord threads 3 by using the ;:~ne-type ~low-line m~thod~ the resl.~lting ring ~ with breaker Z
i5 cut. by any apprDpriate.known method~ e.g.~ oy means of a circular knife in a plane drawn through its axis of rotation. This results in obtainin~
strip 12 (Fig. 4).
Strip 12 is then pl~ced ~nto ~asing 18 (~ig.
~) of apparatus 17 ~or~heating the strip with breaker in whlch the strip i5 inserted between pressure rolls 1~ 20 which are used to impart linear m.otion to strip 12 in a horizcntal plan~.
Strip 12 i5 thus drawn through inductor ~1 which is of rectangular configuration,and which embraces the.cross-section of strip 12 with a mini~um air gap. This results in a 20ne heatlng of metal cD~d threads ~ which ~re present at a c~rrent moment in the zone of influence of rectangular inductor 21.
Owing to the exposure of the ends of all ~etal cord threads~ access of loxygen to these ends and to the ad~acent rubber layers is ensured 50 as to achieve the complete th~rmao:~idation destruetion of,the adjacent ru~er layers for complete th~rmal decomposition of rubber into dry pulverulent 2S techni cal carbon and a hydrocarbon gaseous product without formation of liquid fractions.
To enhance output and lower power requirsments of the praress~ an oY~ygen medium i5 . J - 8 -/

provided in a ~one of the exposed ends o~ metal cord thread~ by supplying oxygen to this zone whi~h is fed through no~zle 22 from bottle 23~
- The met~l cord threads are thus l~berated from the earcass and tread and can be ea:si ly separated ~rom them by any known method, e.g. ? by means of an electromagnet and the like.
- Therefore, pulverizing rubber layers adjacent to metal cord threads without the formation of liquid fractions allows removal-o~ these threads to be substantially facilitated thus enhancing productivity. In addition~ the presence of oxygen in the heating zone ensures the autocatalytic mode O~ ~h~mn~ci~tion destruction of rubber 50 as to lS substantially iower power requirements for the process in comparison with the state of the art method.
The tread and carcass rubber separated from metal card threads is used for maklng single-piece rubber products on blan~ing presses or for producing regenerate. Metal cord threads are also ~sed ~fter reprocessingJ
Dry technical carbon resulting from the thermal treatment is a finished product, and ~S hydrocarbon gas is pump~d from the treatment one and is used as a gaseous fuel so as to ensure a ~o~l~t_ly w7 te-free Drocess ~nd protect the : environment while retaining uti~lity properties of the tread and car~ass parts of rubber.
Industrial ~pplicability The. i nvention may be highly effectively used at regenerating and tire retreading plants and ' al50 at rubber manufacturing plants.
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Claims (4)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method for recovering breaker metal cord threads from rubber tires, comprising heating breaker metal cord threads in a high-frequency electromagnetic field and separating them from rubber, characterized by the fact that a tire is completely cut through the breaker before the heating a in plane drawn perpendicularly with respect to its axis of rotation in such a manner as to expose the ends of all metal cord threads, the heating of the cords being carried out to a temperature of complete thermooxidation destruction of rubber layers nearest to the metal cord threads.

2. A method of claim 1, characterized by the fact that a tire is cut through along both longitudinal borders of metal cord threads to form a ring with breaker and a pair of side walls.

3. A method of claim 2, characterized by the fact that after the complete cutting through the tire along both longitudinal borders of metal cord threads, the resulting ring with breaker is cut in a plane drawn through the axis of its rotation to form a strip.

4. A method of claim 1, characterized by the fact that an oxygen medium is provided in the zone of the exposed ends of metal cord threads in heating metal cord threads by supplying oxygen to this zone.

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