PROCESS OF BUTT WELDING OF TWO PLASTIC PARTS ( VERSIONS ) Russian patent published in 1998 - IPC

FIELD: selective butt welding of parts made from plastic. SUBSTANCE: invention specifically refers to connection of parts produced from polyethylene. In accordance with process each part is provided with identification code in advance. Each code is entered in sequence and into certain positions with data including at least portion of following characteristics: thickness of walls and/or outer diameter of given part at end that should be welded uniaxially to another part ( (б₁) ), temperature or temperature range to which heating element should be heated so that butt of part reaches welding temperature ( (б₂) ), time period during which part should be in contact with heating element ( (б₃) ), time period during which part should be pressed against another part ( (б₄) ), pressure or pressure range that should be applied to part during time periods ( б₄ ), ( (б₅) ), type of plastic ( (б₆) ) from which part is manufactured and yield coefficient or range of yield coefficients ( (б₇) ) of material of part. Then information of mentioned codes is read by scanner and codes are compared by positions. If information obtained with reference to specified characteristics from (б₁) to (б₇) is matched in pairs in two codes in some cases as minimum compatibility of codes and rows of values common for two parts are recognized, number of values are found and entered into welding program loaded into welding set controlled by computer to process these values so that welding of parts by heating element is carried out depending on mentioned values. Heating element heated to preset temperature in advance is placed between conditioned butts of parts, parts are pressed against heating element and joined butts of parts are heated to welding temperature. Then heating element is removed, heated butts are pressed against each other with application of welding pressure, parts are held under pressure and later cooled. EFFECT: diminished probability of errors, safety of welding process and increased reliability of welds independent of practical working conditions. 9 cl, 8 dwg , 2 tbl