909,124. Making honeycomb structures; welding. HEXEL PRODUCTS Inc. Dec. 12, 1958, No. 40183/58. Classes 83 (2) and 83 (4). A honeycomb material is formed of a number of superposed metal sheets, alternate sheets at least being corrugated and the sheets being joined together by welding the nodes of each corrugated sheet to its neighbour. Fig. 17 shows a form in which alternate sheets only are corrugated and Figs. 2 and 19 show forms in which each sheet is corrugated. A machine for resistance welding the sheets together comprises a main frame B, a sheet or web-supporting assembly C mounted on two parallel rods 24 extending along the lower part of the frame B and carrying electrode fingers 101, 102 and a carriage D reciprocally mounted on parallel rods 21 along the upper part of the frame and carrying electrode rollers or wheels 47. The carriage D is traversed by means of a chain 38 secured thereto at 38a and 38b and driven from a motor 32 and clutch 33. Mounted within the frame 25 of the carriage D is a secondary frame 41 which is pivotally and slidably mounted on an axle 42. An insulating block E carrying the wheels 47 is mounted on the lower portion of the frame 41 by means of a T-shaped block 52 slidable between channel members 51 mounted on end walls 44, 45 of the frame 41. The bottom of the block has parallel slots 59, each housing a bar 62, pivotally mounted on an insulating axle 63 and supporting a welding wheel at a bifurcated end, the arms 65a of which bear against the sides of the wheel to make electrical contact therewith. Current is supplied to the rear ends of the bars 62 through leads 69, alternate bars preferably being connected to positive and negative sources respectively. The secondary frame 41 is capable of two movements within the carriage D under the control of doubleacting reciprocating pneumatic motors, a tilting movement about axle 42 under the control of motor 73 and movement along the axle under the control of motor 74. In addition, the electrode block E may be moved transversely by a similar motor 75 to effect a more accurate registration of the wheels with the work. During welding, the wheels are traversed along the work by a longitudinal movement of the carriage D. The assembly C comprises two opposed plates 109, 113 reciprocable by pneumatic motors 134, 135 from which plates extend sets of fingers 101, 102. Spaced from the plates 109 and 113 are finger-guide comb plates 104. The sets of fingers are supported by cam shafts 115, 116, each having identical cam faces 119, 120, the shafts being rotatable by a rack 122 so controlled that it may be driven to two minor positions within two major positions. The control mechanism includes a collar 142 reciprocable along rod 141 by a pneumatic motor 146 between limits determined by adjustable stop collars 143, 144. A pneumatic motor 153 mounted on the collar 142 engages an arm 152 depending from the rack to a position between adjustable stops 156 on a bracket 151 upstanding from the collar. Thus, motor 146 provides the major movement, and motor 153 a secondary adjusting movement, of the rack. Between and mounted on the plates 104 are web-edge aligning combs 161 urged towards their mounting plates by springs but movable away from said plates by inflatable flexible cylinders 163 so as to press on the edge of the work. At the beginning of a welding operation, carriage D is adjacent the rear wall 22 of the main frame and one set of fingers, say 101, supported by combs 164 are below the other set 102 supported by cam faces 120. A web 14 is placed on fingers 101 and another on fingers 102 with the welding nodes abutting and the combs 161 are then forced together to align the edges of the webs. The motor 32 may then be actuated to traverse the carriage D under the control of a forward-reverse clutch 33 operated through relays under the control of limit switches 191 and 197. The pneumatic motor 73 normally holds the welding wheels above the work area but they are lowered on to the work when a cam plate 210 actuates arms 208, 209 of switches 206, 179. The welding wheels are again raised when they have passed the work area. When arm 198 engages stop collar 199, switch 197 is closed and the carriage D reversed, welding wheels remaining up and welding current off. After a welding operation it is desirable to raise the upper set of fingers 102 to break any welds that may have formed between the work and the lower fingers, after which the lower fingers 101 are withdrawn and raised, the upper fingers 102 lowered together with the work by means of the cams 116 and the fingers 101 moved forwardly again above the fingers 102 ready to receive a new web. The shifting of the sets of fingers moves the welding truck by one half the distance between the nodes and re-registration of the welding wheels is effected by the motor 75. All these movements are effected by means of switches, relays and the various pneumatic motors.