IL27742A - Methods of welding thermoplastic material - Google Patents

Description

E R ST S E G H N D J t S D i T mm ARNAN GABRIELI Ί K 1426 PATENTS FORM 3 PATENTS AND DESIGNS ORDINANCE METHODS OP WELDING THERMOPLASTIC MATERIAL SPECIFICATION Swiss body of Dreispitzstresse 4000 B a s 1 do hereby declare the nature of this invention and in what mariner the same is to be to be particularly described and ascertained in and by the following The present invention relates to methods of welding gether members made of thermoplastic the welding of members such as sheets and tubes of thermoplastic material by means of heated tool welding or press butt it is usual for portions of the members which are to be welded together to be first heated to the welding perature and then pressed together until they have The welding temperature for any material is a temperature which is known to the expert and at which the material is For the purpose of pressing the parts together use is made of pressures of the order of to 2 In some pressures of up to about 5 cm have been which caused a reduction in the quality of the The advantages of welds are the higher the pressure the larger will be the weld beads between which a ful notch Even if the beads are removed again by subsequent so that a notch is no longer present on the the quality of the weld is not substantially The present invention consists in a method of welding together members made of thermoplastic in which portions of the members to be welded together are first heated to welding temperature and then pressed which method comprises the steps of applying mould parts to each side of the said portions to prevent the thermoplastic material from spreading perpendicular to the direction in which the said portions are pressed and the said portions together with a pressure of form The pressure exerted on the said portions may be less than 20 the moulds being The moulds may be preheated to a temperature which is at least halfway between room temperature and the welding perature and at most below the welding temperature The welding may either press butt welding or lap and the said portions may be for by ed other radiation by contact with a heating by a flame by induction heating or by other known To make the invention more readily reference is now made to the accompanying which are given by way of and wherein Figure in longitudinal the press butt welding of two sheets 2 shows a taken on the line S of Figure 1 s Figure 3 in longitudinal the press butt welding of two tubes of equal Figure 4 shows a ection taken on the line of Figure Figure 5 in longitudinal the butt welding of branch tube to a tubes and Figure 6 in longitudinal the lap welding of of two Figures I and 2 illustrate the press butt welding together of two sheets 1 and 2 of a hard polyvsnylchlo The edge portions first heated to welding temperature in kno n for example contact with a suitable heating as is in press butt The edge portions are then inserted into a which here consists of a trough 3 and a the section of the space bounded by these two parts of the mould ding to the section of the sheets 1 and Before the insertion of the sheets 1 and this mould is heated to a temperature which is at least halfway between room temperature and the welding o temperature and at most O C below the welding The lid 4 is then made fast to the trough 3 by means of locks 5 or by means of clamps or other devices The sheets 1 and 2 are then pressed against one another by a force F which at the weld produces a minimum pressure of 10 but which should not exceed SO cm if the mould has the mould has not been the pre assure should amount to at least 20 cm and at most 0 After about one minute the s I and 2 are joined together so effectively that the mould can be opened and the workpiece removed and completely cooled in the The weld seam tained in this manner naturally has no weld bead and naturally also no Tests have revealed that the high pressures not only bring about a strengthening of the material but also cause the material of the sheets 1 fend into one so that the surface at which the sheets 1 and 2 are join ed together The method naturally be carried out by machine and cally without In Figures 3 and two tubes 6 and 7 of polyethylene arc shown being welded together End portions 6a and 7a of the tubes 6 and 7 heated to a welding temperature and then a metal cylinder which is provided with a rod and which together with a metal hollow cylinder has been is inserted into one of the tubes 6 and The cylinders 8 and 9 form a mould which prevents the material of the tubes 6 and 7 from spreading dicularly to the direction in which a pressure F is applied to press the end portions 6 and 7 The pressure F applied either by means of pressure plates 10 or pressure rings of which one each have been shown in Figure The tudinal axes of the tubes 6 and 7 need not be but it may antage ous for the tubes 6 and 7 to be installed with their axes the force F being applied only from in which case the force F has to be such that at the weld it produces a pressure of 10 to 50 cm in the event of the cylinders 8 and 9 being or to 100 cm if the cylinders 8 and 9 are not preheated Figure 5 shows a branch piece being made from polypropylene by welding into the wall of a tube an opening being simultaneously or subsequently cut in the wall of the tube through the tube The portions of the tubes and which are to be welded together are first heated to the welding whereupon a preheated mould is the mould the tube a cylinder 15 in the tube and a hollow flanged cylinder 16 fitted externally over the tube The hollow flanged cylinder 16 is fastened to the tube 12 by means of bands 17 and To a pressure ring there is then applied a force F which is so proportioned that a pressure of from 10 to 50 cm is produced at the As in the previously described methods shown in Figures 1 to the mould prevents the material from spreading perpendicular to the direction of the force thus the formation of weld beads and of a notch lying while the pressure applied brings about a stantial enlargement of the weld surface since that the materials of the tubes 1 and flow into one Figure 6 shows a lap weld being made between two sheets 18 and 20 of hard portions 19a and 20a of which are first heated to welding temperature Two metal bars 21 and which may be fastened to a work serve as mould for preventing the plastic material from spreading perpendicular to the direction fo the pressure The force F necessary for the welding exerted on pressure plates 23 and 24 and produces a pr of 10 to 50 cm at the The preheating of the bars 21 and 22 and the plates 23 and 24 may be dispensed withjif the pressure amounts to a minimum of 20 particularly described ascertained nature of my said and in manner the same is to be declare that what claim is insufficientOCRQuality

Claims (1)

1. A method of welding together members made of thermoplastic material,, in which portions of the members to be welded together are first heated to a welding temperature and then pressed togethe „ which method comprises the steps of applying mould parts to each side of the said portions to prevent the thermoplastic material from spreading perpendicular to the direction in which the said portions are pressed together, and pressing the said portions together with a pressure of from to kg/square cm. A method as claimed in claim in which the pressure exerted on the said portions is lees than kg/square cm, and the moulds are preheated. A method as claimed in claim or in which that the moulds are preheated to a temperature which is at least halfway between room temperature and the welding temperature and at most °C below the welding temperature . A method of welding substantially as hereinbefore described with reference to and as illustrated in Figures and of the accompanying drawing . A method of welding substantiall as hereinbefore described with reference to and as illustrated in Figures and of the accompanying drawing -6. A method of welding substantially as hereinbefore described with reference to and as illustrated an Figures of the accompanying drawing ¾