Patent Application
20150099068
The invention relates to a steel cord for extrusion process, and in particular to a steel cord where a steel wire is connected to the leading end of the steel cord. This invention also provides an apparatus, a change-over process, and the use of steel cord incorporating present invention.
Elevator rope as disclosed in WO2004/076327A1, and cable as disclosed in WO03/044267A1 are widely used, wherein a steel cord is coated with a polymer material through extrusion process, as disclosed in BE1006346. In the extrusion process, the change over time for re-load new steel cord is too long, because new steel cord cannot go through the extruder head when the extruder head is full of polymer, while the polymer will burn inside the extruder head when the heating is not turn off during change over. Therefore, the change-over may comprise following step: stop the extruder, turn off the heating, cool the extruder head, remove the extruder head, open the extruder head and remove the remaining polymer inside, reload the extruder head, insert new steel cord through the extruder head, turn on the heating, start the extruder, fine tune the process parameter to resume production. Since there may be 2 to 140 and more steel cords for the extrusion process, the change-over of steel cord on an extruder is long. In a typical application, where 12 steel cords are to be coated with polymer simultaneously, the change-over time is around 8 hours because the extruder head needs to be re-heated to about 500° C. in an oven to remove the PU remained inside. Therefore, industry is looking for solutions to cut the change-over time and boost the productivity.
The primary object of the invention is to provide a steel cord to facilitate the change-over of extrusion process. It is also the objective of present invention to provide the use of the steel cord for abovementioned extrusion process.
According a first aspect of the invention a product is claimed that a steel cord is characterized in that a steel wire is connected to the leading end of said steel cord, wherein the leading end means the end of steel cord which is on the surface of steel cord spool.
The inventive product relates to the combination of features as described in claim 1. Specific features for preferred embodiments of the invention are set on in the dependent claims.
According to present invention, the steel wire is welded to the leading end of said steel cord. Besides, other ways of connection can be brazing, soldering, and gluing.
According to present invention, the diameter of the steel wire is not greater than the diameter of the steel cord. Preferably the diameter of the steel wire is between 60% to 100% of the diameter of the steel cord, and more preferably the diameter of the steel wire is between 90% to 98% of the diameter of the steel cord.
According to present invention, the surface of the steel wire is harder than zinc, and preferably the steel wire is either a stainless steel wire or a steel wire coated with a coating harder than zinc, wherein the coating can be a copper coating, a brass-coating, a nickel coating, or a chromium coating.
According to present invention, the leading end of the steel wire is chamfered or rounded to facilitate the insertion of steel wire through the extruder head.
According a second aspect of the invention an apparatus is claimed that an assembly of steel cord according to claim 1 and an extruder having an extruder head, wherein the length of the steel wire is greater than the length of extruder head.
According a third aspect of the invention a process is claimed that a process for change steel cord on an extruder is characterized by following steps:
a. stop the extruder and remove remaining steel cords
b. insert the steel wire of the steel cord according to claim 1 through the extruder head;
c. pull the steel wire and lead the steel cord through the extruder head;
d. cut off the steel wire;
e. start the extruder and resume production.
According a fourth aspect of the invention a method is claimed that the use of a steel cord as claimed in claim 1 for extrusion process.
Preferred embodiments of the present invention will be described herein below with reference to the accompanying figures.
A first embodiment is illustrated in
The steel wire 6 can be welded to the leading end 8 of the steel cord 2 as disclosed in WO2003/100164A1, while other ways of connection can be brazing, soldering, and gluing as disclosed in WO2004/007833A1. Since leading steel cord through extruder head may needs a few hundred newton, welding and other ways of connections will do. Compared with other ways of connection, welding is a very good option, because in the extrusion process the connection will go through the extruder head which is heated at a temperature as high as 230° C. and the connection between the steel cord and steel wire can be maintained.
A mechanical test on a specimen shows following data
While the According to present invention, the surface of the steel wire is harder than zinc, and preferably the steel wire is either a stainless steel wire or a steel wire coated with a coating harder than zinc, wherein the coating can be a copper coating, a brass-coating, a nickel coating, or a chromium coating.
Firstly, the surface of the steel wire is harder than zinc, because the steel wire is to be inserted through the extruder head and the hard surface of the steel wire is to guarantee that the steel wire is not to be cut and jam inside the extruder head. Secondly, a stainless steel wire is a good option, because not only stainless steel wire itself is strong enough but also the surface of stainless steel wire is hard enough to go through the extruder head. Thirdly, a steel wire coated with a coating harder than zinc, for example, a copper coating, a brass-coating, a nickel coating, or a chromium coating, is also a good option, because not only steel wire itself is strong enough but also the surface of the coated steel wire is hard enough to go through the extruder head.
According to present invention, the leading end of the steel wire is chamfered or rounded to facilitate the insertion of steel wire through the extruder head.
l
The process for change steel cord incorporating present invention on an extruder is characterized by following steps:
a. stop the extruder and remove remaining steel cords;
b. insert the steel wire of the steel cord according to claim 1 through the extruder head;
c. pull the steel wire and lead the steel cord through the extruder head;
d. cut off the steel wire;
e. start the extruder and resume production.
Since the steel wire is strong and can be easily inserted through the extruder head, it is not necessary to stop the heating of the extruder, because the changeover of steel cord can be done in a minute.
The use of the steel cord incorporating present invention for extrusion process.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2012/073460 | 11/23/2012 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2011/083051 | Nov 2011 | US |
| Child | 14360729 | US |
