METHOD FOR ADHESIVELY BONDING HELICOPTER ROTOR BLADE ASSEMBLIES

• US 3,607,545 A
• Filed: 08/08/1968
• Issued: 09/21/1971
• Est. Priority Date: 08/08/1968
• Status: Expired due to Term

• Current Assignee: Jack L. Ritchey, John T. Parsons
• Original Assignee: Jack L. Ritchey, John T. Parsons
• Inventors: Ritchey, Jack L., Parsons, John T.
• Primary Examiner(s): Epstein, Reuben
• Application Number:
  US04/751,297
• Time in Patent Office: 1,139 Days
• Field of Search: 156/311,321,583
• US Class Current: 156/311
• CPC Class Codes: B64C 2027/4736 from composite materials
• CPC Class Codes: B64C 27/473 Constructional features
• CPC Class Codes: G05D 23/1909 whose output amplitude can only take two discrete values
• CPC Class Codes: G05D 23/22 the sensing element being a thermocouple
• CPC Class Codes: H05B 3/00 Ohmic-resistance heating

Abstract

Method for controlling the heating and cooling steps in adhesive bonding of helicopter rotor blades and similar articles containing metal masses which serve as heat sinks. To bring the temperature at the adhesive bond line equally to flow temperature, local heaters, which roughly define separate zones of a metal pressure fixture, are separately energized to raise the zone temperatures unequally, to compensate for the local drain of heat into the heat sink. For cooling, liquid is pumped through passages while the local heaters cycle on as required to equalize the rate of cooling.

Claims

2. Method according to claim 1, wherein when said heat survey sample is enclosed in said fixture, heat energy is initially applied to the heating zones of said fixture in incremental steps according to a trial program in which relatively more heat energy is applied to those heating zones overlaying large masses of assembly material which would be expected to act as localized heat sinks, wherein the progressions of temperatures at the assembly bond lines and at the overlaying heating zones of the fixture are sensed during each incremental step, the sensing of the progressions of temperatures at the assembly bond lines being by means of flat temperature sensors disposed at intervals in the heat survey sample bond lines, the sensing of the progressions of temperatures in the heating zones of the fixture being by means of a temperature sensor in each heating zone, each successive incremental step of said trial program being performed only after substantial uniformity of bond line temperatures is reached, and wherein upon completion of said trial program, the timed heating program is revised to cause the application of more heat energy to the fixture heating zones overlaying those areas of the assembly bond lines wherein the temperature rise was observed to lag behind that of adjacent areas.

3. Method according to claim 1, further including the step of cooling the bonding fixture down from curing temperatures by modulating the cooling of each heating zone by applying such amounts of heat energy thereto as necessary to reduce its temperature according to a predetermined cooling program wherein more heat energy is applied to the fixture heating zones overlaying those areas of the assembly bond lines which tend to cool more rapidly than adjacent areas.