Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1993-07-06
1996-06-18
Maki, Steven D.
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
1563042, 156358, 156378, 156499, 156503, B29C 6520
Patent
active
055274064
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method of fusing adjacent surfaces of a pair of separate bodies made from thermoplastic, fusible material.
European patent application No. 0 196 795 discloses an apparatus for fusion joining of thermoplastic pipes. This known apparatus comprises a pair oppositely arranged clamps which are moveable in relation to a frame towards and away from each other by means of hydraulic cylinders or rams. The free ends of a pair of thermoplastic pipes for natural gas distribution are mounted in the respective clamps so that the end surfaces of the pipes may be moved into engagement with opposite surfaces of a heater plate arranged therebetween by means of the rams. The hydraulic pressure in the rams is increased to a certain pressure level (drag pressure) at which the clamps and the pipe ends clamped thereby start moving towards the heater plate. Such movement is detected by a limit switch, and a microprocessor-based control system adds a pre-programmed value of pressure (bead-up pressure) to the drag pressure so that the pipe ends are forced against the opposite surfaces of the heater plate to form end beads thereon. While the drag pressure is mainly the pressure necessary to overcome frictional forces acting on the pipes, the clamps and other moveable parts connected thereto, the bead-up pressure is the pressure determining the surface pressure obtained between the heater plate at the pipe end surfaces.
After heating for a pre-programmed period the control system automatically initiates reduction of the hydraulic pressure and retraction of the heater plate. Immediately thereafter the heated thermoplastic pipe ends are forced together (fusion) for another programmed period of time, and the hydraulic pressure applied is the sum of the recorded drag pressure and a pre-programmed added pressure (fusion pressure), the pre-programmed fusion pressure being chosen so as to correspond to the desired pressure per unit of area of the pipe end surfaces during fusion.
In order to secure that the fusion joint is without any defects and that substantially the same quality of the fusion joints (for example in accordance with certain standards or regulations) is obtained by a number of successive uniform fusion operations, it is important that the bead-up pressure and the fusion pressure do not vary to any appreciable extent from time to time and that said pressures are kept at the prescribed values. In using the known apparatus described above the drag pressure being measured is the hydraulic pressure necessary to cause movement of the clamp and of the pipe or tube gripped thereby. This means that the friction to be overcome is the resting friction and not the sliding friction which is lower. Consequently, the actual pressure applied to the end surfaces of the pipe or tube ends during the bead-up and fusion procedures are not exactly the pre-programmed pressures added to the drag pressure, when the known apparatus is used.
The present invention provides a method of fusing adjacent surfaces of a pair of separate bodies, such as solid rod-shaped bodies or tubular bodies, made from thermoplastic, fusible material. The method according to the invention comprises forcing the surfaces of the bodies into abutting engagement with respective opposite surfaces of a heating device, heating the opposite surfaces of the heating device to a predetermined temperature at least equal to the temperature of fusion of the thermoplastic material, maintaining the thermoplastic bodies into contact with the heated opposite surfaces of the heating device for a predetermined period of time so as to heat the abutting surfaces of the bodies to a temperature at least equal to the temperature of fusion of the thermoplastic material, removing the heating device from the heated surfaces of the bodies, and forcing the heated surfaces of the thermoplastic bodies into mutual engagement so as to fuse said bodies, and the method according to the invention is characterized in measuring the pressure between said body surfaces by arrangi
REFERENCES:
patent: 3013925 (1961-12-01), Larsen
patent: 3372577 (1968-03-01), Bates et al.
patent: 4263084 (1981-04-01), Takala
patent: 4640732 (1987-02-01), Stafford
patent: 4957570 (1990-09-01), Jenkins et al.
patent: 4974454 (1990-12-01), Wolfer et al.
patent: 5013376 (1991-05-01), McElroy et al.
patent: 5051148 (1991-09-01), Resch
Brath ApS
Maki Steven D.
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