DRYING METHOD

Abstract

A method for welding hygroscopic plastics parts, preferably pipeline components, by means of a butt-welding machine, wherein the two plastics parts are clamped and fixed in a coaxial position in relation to one another by means of a clamping device.

Claims

1. A method for welding hygroscopic plastics parts (1), preferably pipeline components, by means of a butt-welding machine, comprising wherein the two plastics parts (1) are clamped and fixed in a coaxial position in relation to one another by means of a clamping device, wherein the mutually opposite end faces of the plastics parts (1) are planed flat by means of a planer which can be brought in between them, and the ends of the plastics parts (1) are melted by means of a heating mirror (2) that can be brought between them, wherein the heating mirror (2) is disposed at a spacing (3) from the end faces of the ends of the plastics parts (1), in order to achieve the required heat for the melting operation, wherein the ends of the plastics parts (1) are joined together after the melting operation, wherein the ends of the plastics parts (1) are dried while the plastics parts are being fixed on the butt-welding machine, wherein the drying is performed by the heating mirror (2) disposed between the ends of the plastics parts (1).

2. A method according to claim 1, wherein the ends of the plastics parts (1) are dried after the planing-flat operation.

3. A method according to either of claim 1, wherein the end faces of the plastics parts (1) are disposed at a greater spacing (3) from the heating mirror (2) for the drying than they are during the melting operation.

4. A method according to claim 1, wherein the ends of the plastics parts are dried before the melting operation.

5. A method according to claim 1, wherein the drying is carried out dynamically and the spacing between the end faces of the plastics parts (1) and the heating mirror (2) is regulated depending on the temperature prevailing at the end of the plastics parts (1), or the welding zone.

6. A method according to claim 1, wherein the ends of the plastics parts (1) are not melted during the drying.

7. A method according to claim 1, wherein, to determine the spacing (3) after the planing-flat operation, a zero-point check of the ends of the plastics parts (1) is performed.

8. A method according to claim 1, wherein the temperature of the heating mirror (2) is kept constant during the drying.

9. A method according to claim 1, wherein the temperature of the heating mirror (2) is kept constant throughout the welding process.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 shows a schematic representation of the sequence of the welding method according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0023] The drawing represented in FIG. 1 shows a schematic representation of the method according to the preferred embodiment of the invention for welding hygroscopic plastics parts 1, preferably pipeline components. Pipeline components are understood to mean, in addition to pipelines, also fittings and other components which together can be welded to one another on a butt-welding machine. FIG. 1 shows the different steps of the method after the planing operation. Image A schematically shows the disposition of the plastics parts 1 with respect to the heating mirror 2 during the method step of drying. It can be clearly seen that the ends of the plastics parts 1 have a distance 3 from the heating mirror which is considerably greater than it is during the next method step of melting B. It can be clearly seen in image B that the distance 3 has been reduced, in order that a higher temperature is generated at the ends of the plastics parts, or in the welding zone, by moving the ends of the plastics parts 1 closer to the heating mirror 2. Since the drying is dynamic, the temperature in the welding zone is regulated by modifying the spacing 3 during the drying phase, in order to obtain optimum drying and avoid melting. Image C shows the position in which the melted ends of the plastics parts are joined together after the heating mirror has been removed and a weld seam 4 is formed.