GB2066404A

GB2066404A - Welding of thermoplastics sections

Info

Publication number: GB2066404A
Application number: GB7940610A
Authority: GB
Original assignee: FAIMER OF BABINI FELICE
Current assignee: FAIMER OF BABINI FELICE
Priority date: 1979-11-23
Filing date: 1979-11-23
Publication date: 1981-07-08
Also published as: GB2066404B

Abstract

A method of welding together hollow thermoplastics sections comprises introducing into an open end of each section (1) an insert (3) of thermoplastic material having at one end thereof a plurality of laterally extending lugs (6, 7, 8 and 9), such that said lugs rest on the edge (5) of said open end; and thermally welding the open ends and associated inserts of two thermoplastic sections in end- to-end relationship so as to fuse together said lugs and sections. Preferably, the interior of each hollow section is provided with longitudinal ribs and each insert is provided with grooves engageable therewith. <IMAGE>

Description

SPECIFICATION Welding of thermoplastics sections The invention relates to the welding together of hollow thermoplastic sections, especially for the formation of frame-like structures, and to thermoplastic sections and inserts for use therein.

At present, sections of thermoplastics material are firmly welded together by known techniques e.g. by interposing a thin metal plate electrically heated to a temperature of 1 90-2500C between the ends to be welded. After the ends have been heated sufficiently to soften the thermoplastic material, the thin plate is removed and the two sections pressed together to effect the weld.

However, in the vicinity of the welded seam, the thermoplastic material may be degraded thereby impairing its stress strength. Thus, the weld presents a line of weakness which is susceptible to breakage, particularly if the weld is at a corner of a frame constructed from the sections.

The present invention seeks to mitigate these disadvantages and moreover to provide a strengthening element in the weld region.

Thus, the present invention provides a method of welding together hollow thermoplastics sections, which comprises introducing into an open end of each section an insert of thermoplastic material having at one end thereof a plurality of laterally extending lugs, such that said lugs rest on the edge of said open end; and thermally welding the open ends and associated inserts of two thermoplastic sections in end-to-end relationship so as to fuse together said lugs and sections.

In order to make right angle corners, the open end of each section and the said one end of the insert may be inclined at 45 degrees to the longitudinally direction prior to welding.

The invention in a further aspect also provides the combination of a hollow thermoplastics section and an insert for use in the method, the insert being of thermoplastic material and having at one end thereof a plurality of laterally extending lugs, such that when said insert is introduced into an open end of the section the lugs rest on the edge of the open end.

In order to more securely fit the insert into the hollow section, the interior of each hollow section may be provided with longitudinal ribs and each insert may be provided with grooves engageable with said ribs.

The invention also extends to an insert for use in the combination formed of a thermoplastic material and having at one end thereof a plurality of laterally extending lugs. Preferably the lugs stand proud of said one end with respect of longitudinal direction of the insert, so that welding only involves fusion of the lugs with each other and with the open ends of the sections. Thereby, thermal deformation of the open ends of the sections is avoided and a strong join results.

An embodiment of the invention will now be described with reference to the drawing wherein Figure 1 shows a perspective view of a hollow section and insert having their ends inclined at 45 degrees for the formation of a corner; Figure 2 shows a schematic longitudinal section prior to the welding of two thermoplastic sections; Figure 3 shows a view similar to that of Fig. 2 after welding has been carried out; and Figure 4 shows a schematic perspective view of the welded corner of Fig. 3.

Figure 1 shows the open end of a hollow thermoplastics section 1 having an interior cavity 2 and a cut edge 5 inclined at 45 degrees to the longitudinal direction of the section. Insert 3, also of thermoplastics material, is a good fit inside the cavity 2 of the section 1 and is provided with longitudinally extending grooves 10 for engaging ribs 11 provided on the interior surface of section 1. The insert 3 also comprises laterally extending lugs 6, 7, 8 and 9 which extend laterally beyond the remainder of the insert 3 and rest on the edge 5 5 of section 1 when the insert is introduced into the open end of the section 1. The lugs thus prevent the insert from passing too far into the interior of the section 1. The lugs also stand proud of the insert 3, considered in the longitudinal direction for facilitating spot-welding.

As shown in Figs. 2 to 4, in order to join two sections together, an insert 3 is introduced into the open end of each section 1 and the sections are brought together, as shown in Fig. 2. Welding is then carried out by conventional techniques so as to fuse together not only the abutted lugs but also the areas of the edges 5 of the sections with which the lugs come into contact. Figures 3 and 4 show a finished welded corner. It will be noted that as well as facilitating welding, the welded inserts provide additional stiffening and strengthening of the thermoplastics sections in the region of the weld.

It will be appreciated that the invention is applicable not only to thermoplastics sections whose edge when viewed in cross-section defines a closed path but also with thermoplastics sections whose cross-section defines a discontinuous path e.g. of C-section, U-section or V-section, such that an internal space or cavity for receiving the insert is provided.

1. A method of welding together hollow thermoplastics sections, which comprises introducing into an open end of each section an insert of thermoplastic material having at one end thereof a plurality of laterally extending lugs, such that said lugs rest on the edge of said open end; and thermally welding the open ends and associated inserts of two thermoplastic sections in end-to-end relationship so as to fuse together said lugs and sections.

2. A method according to claim 1, wherein the open end of each section and said one end of the insert is inclined at 45C to the longitudinal direction, and the two sections are welded to form a right angle bend.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Welding of thermoplastics sections The invention relates to the welding together of hollow thermoplastic sections, especially for the formation of frame-like structures, and to thermoplastic sections and inserts for use therein. At present, sections of thermoplastics material are firmly welded together by known techniques e.g. by interposing a thin metal plate electrically heated to a temperature of 1 90-2500C between the ends to be welded. After the ends have been heated sufficiently to soften the thermoplastic material, the thin plate is removed and the two sections pressed together to effect the weld. However, in the vicinity of the welded seam, the thermoplastic material may be degraded thereby impairing its stress strength. Thus, the weld presents a line of weakness which is susceptible to breakage, particularly if the weld is at a corner of a frame constructed from the sections. The present invention seeks to mitigate these disadvantages and moreover to provide a strengthening element in the weld region. Thus, the present invention provides a method of welding together hollow thermoplastics sections, which comprises introducing into an open end of each section an insert of thermoplastic material having at one end thereof a plurality of laterally extending lugs, such that said lugs rest on the edge of said open end; and thermally welding the open ends and associated inserts of two thermoplastic sections in end-to-end relationship so as to fuse together said lugs and sections. In order to make right angle corners, the open end of each section and the said one end of the insert may be inclined at 45 degrees to the longitudinally direction prior to welding. The invention in a further aspect also provides the combination of a hollow thermoplastics section and an insert for use in the method, the insert being of thermoplastic material and having at one end thereof a plurality of laterally extending lugs, such that when said insert is introduced into an open end of the section the lugs rest on the edge of the open end. In order to more securely fit the insert into the hollow section, the interior of each hollow section may be provided with longitudinal ribs and each insert may be provided with grooves engageable with said ribs. The invention also extends to an insert for use in the combination formed of a thermoplastic material and having at one end thereof a plurality of laterally extending lugs. Preferably the lugs stand proud of said one end with respect of longitudinal direction of the insert, so that welding only involves fusion of the lugs with each other and with the open ends of the sections. Thereby, thermal deformation of the open ends of the sections is avoided and a strong join results. An embodiment of the invention will now be described with reference to the drawing wherein Figure 1 shows a perspective view of a hollow section and insert having their ends inclined at 45 degrees for the formation of a corner; Figure 2 shows a schematic longitudinal section prior to the welding of two thermoplastic sections; Figure 3 shows a view similar to that of Fig. 2 after welding has been carried out; and Figure 4 shows a schematic perspective view of the welded corner of Fig. 3. Figure 1 shows the open end of a hollow thermoplastics section 1 having an interior cavity 2 and a cut edge 5 inclined at 45 degrees to the longitudinal direction of the section. Insert 3, also of thermoplastics material, is a good fit inside the cavity 2 of the section 1 and is provided with longitudinally extending grooves 10 for engaging ribs 11 provided on the interior surface of section 1. The insert 3 also comprises laterally extending lugs 6, 7, 8 and 9 which extend laterally beyond the remainder of the insert 3 and rest on the edge 5 5 of section 1 when the insert is introduced into the open end of the section 1. The lugs thus prevent the insert from passing too far into the interior of the section 1. The lugs also stand proud of the insert 3, considered in the longitudinal direction for facilitating spot-welding. As shown in Figs. 2 to 4, in order to join two sections together, an insert 3 is introduced into the open end of each section 1 and the sections are brought together, as shown in Fig. 2. Welding is then carried out by conventional techniques so as to fuse together not only the abutted lugs but also the areas of the edges 5 of the sections with which the lugs come into contact. Figures 3 and 4 show a finished welded corner. It will be noted that as well as facilitating welding, the welded inserts provide additional stiffening and strengthening of the thermoplastics sections in the region of the weld. It will be appreciated that the invention is applicable not only to thermoplastics sections whose edge when viewed in cross-section defines a closed path but also with thermoplastics sections whose cross-section defines a discontinuous path e.g. of C-section, U-section or V-section, such that an internal space or cavity for receiving the insert is provided. CLAIMS

3. A method of welding substantially as described with reference to and as shown in the drawing.

4. The combination of a hollow thermoplastic section and an insert for use in the method of any preceding claim, the insert being of thermoplastic material and having at one end thereof a plurality of laterally extending lugs, such that when said insert is introduced into an open end of the section the lugs rest on the edge of said open end.

5. The combination according to claim 4, wherein the interior of each hollow section is provided with longitudinal ribs and each insert is provided with grooves engageable with said ribs.

6. The combination according to claim 4 substantially as described with reference to and as shown in the drawing.

7. An insert for use in the combination of claim 4 formed of a thermoplastic material and having at one end thereof a plurality of laterally extending lugs.

8. An insert according to claim 7, wherein the lugs stand proud of said one end with respect to the longitudinal direction of the insert.

9. A thermoplastic insert substantially as described with refrence to and as shown in the drawing.