Plastic and nonmetallic article shaping or treating: processes – With measuring – testing – or inspecting
Patent
1996-11-22
1998-07-28
Silbaugh, Jan H.
Plastic and nonmetallic article shaping or treating: processes
With measuring, testing, or inspecting
264 405, 2642094, 2642095, 2642902, 425140, 425325, 425384, 425392, B29C 4790
Patent
active
057859060
DESCRIPTION:
BRIEF SUMMARY
BACKKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing biaxially oriented tubing from thermoplastic material, comprising forcing the tube over a mandrel at an orientation temperature of the plastic material, which mandrel comprises an expansion part which produces expansion in the circumferential direction of the tube, while downstream of the mandrel an axial pulling force is exerted on the tube, and the biaxially oriented tube is cooled down, and downstream of the mandrel the tube is subjected to calibration of its external dimensions. In the context of the present invention the term tube also relates to hose-type products.
2. Description of the Prior Art
The object of biaxially orienting the plastic material of a tube, also known as biaxially drawing a tube, is to improve the properties of the tube through orientation of the molecules of the plastic material of the tube in two mutually perpendicular directions. In the case of a certain known method the biaxial orientation is produced by forcing the tube over a mandrel, with the result that the tube is deformed. Upstream of the mandrel the tube is brought to a suitable orientation temperature. In practice, the temperature distribution inside the tube wall is within a suitable range for biaxial orientation of the molecules of the plastic material of the tube.
In the case of the known method the tube is forced over the mandrel through an axial pulling force being exerted on the tube downstream of the mandrel. The mandrel comprises an expansion part which produces the increase in the dimensions in the circumferential direction of the tube. The fact that the tube passes over this expansion part essentially determines the orientation of the plastic material in the circumferential direction of the tube. The axial pulling force essentially determines the orientation in the axial direction. The biaxial orientation obtained is fixed (frozen) by cooling down the tube.
A method of the type mentioned in the preamble is known from, for example, WO 93/19924. This publication describes how a tube with a cylindrical tube wall is manufactured by means of an extruder. Viewed in the direction of movement of the tube, a solid, undeformable mandrel with a conical expansion part is situated downstream of said extruder. The tube is forced over the mandrel at an orientation temperature which is suitable for the plastic material concerned, through an axial pulling force being exerted on the tube downstream of the mandrel. At the level of a run-off part of the mandrel, connected to the expansion part of the mandrel, the tube is cooled externally in order to fix the orientation obtained.
In order to guarantee that the ultimately manufactured biaxially oriented tube has the desired external dimensions--in this case external diameter--with sufficient accuracy, this publication proposes that a vacuum calibration sleeve should be placed downstream of the mandrel, between the mandrel and the pulling device. The tube is pulled through this calibration sleeve, in the course of which the tube is sucked against the inside wall of the calibration sleeve by means of a vacuum created by a vacuum source. The result of this is that the tube is stretched here in the circumferential direction until it reaches an external diameter determined by the inside wall of the calibration sleeve. In order to make stretching of the tube possible, the tube has to be heated in the case of this known method. The heating is carried out by heating the calibration sleeve.
The method of calibration of the external dimensions of the biaxially oriented tube proposed in the case of this known method has proved disadvantageous. In particular, it has been found that the biaxial orientation of the plastic material of the tube produced during the passage over the mandrel is impaired in an undesirable way, both through increasing the external dimensions of the tube during calibration and through heating applied to the tube during the calibration.
The object of the
REFERENCES:
patent: 2423260 (1947-07-01), Slaughter
patent: 3296661 (1967-01-01), Moustier
patent: 3812230 (1974-05-01), Takahshi
patent: 4020136 (1977-04-01), Zaro
patent: 4028037 (1977-06-01), Dawson
patent: 4314958 (1982-02-01), Macloed et al.
patent: 4613532 (1986-09-01), Michel et al.
patent: 5096634 (1992-03-01), Tsadares et al.
patent: 5516270 (1996-05-01), Lehtinen
Prenger Jan Hendrik
Schuurman Johan
Visscher Jan
Eashoo Mark
Silbaugh Jan H.
Wavin B.V.
LandOfFree
Method and device for manufacturing biaxially oriented tubing fr does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device for manufacturing biaxially oriented tubing fr, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for manufacturing biaxially oriented tubing fr will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-20468