Patent GB-890685-A (GB)
Title: Apparatus for manufacturing corrugated sheet metal strip for heat interchange fin structures
IPC: B21D53/02
Filed: 1958-07-10
Abstract: 890,685. Making heat exchangers; corrugating; unreeling; shearing. DUNHAM-BUSH Ltd. July 10, 1958 [July 12, 1957], No. 22178/58. Classes 83 (2) and 83 (4). Apparatus for producing corrugated sheet metal strip comprises a press having a reciprocating head, a die assembly having a reciprocating die unit mounted upon said head which co-operates with a stationary die unit, said reciprocating die unit including a corrugating die blade and a pilot die blade which projects into each formed corrugation so as to push and hold the corrugated portion of the sheet metal during the corrugating operation, said stationary die unit including die blades forming open slots in which the corrugations are formed and nested and a stripper unit which has stripper blades spring-urged into said slots and which move the corrugations therefrom as the reciprocating die blades are withdrawn and feed means for advancing the sheet metal strip during each period of withdrawal of the reciprocating die unit. Corrugating and unreeling.-The apparatus comprises a reciprocating head 11 supported on a frame 12 which also carries a platform 24 of which is mounted a supply reel 26 for the metal strip. The reel is intermittently driven by an electric motor. As the strip is uncoiled it passes through a guide 36 and over a guide 38 and into the machine feed mechanism 40 which consists of a hold-down leaf spring 48 and a pivoted ratchet dog 50. The feed mechanism is reciprocated so that the dog engages and feeds the strip step-by-step into the corrugating dies through a pivoted tunnel guide and feeler unit 52. When the guide swings from its normal horizontal position a switch 54 is closed to stop the apparatus. Just before the die assembly the strip passes between a stationary guide plate 60 and a spring-loaded pivoted dog 62. The die assembly 58 (Fig. 11) comprises an upper pilot blade 66 and an upper corrugating die blade 68 which co-operate with a lower die assembly formed by three parallel spaced apart blades 63, 65 and 67 mounted on a die block 69. The pilot blade 66 which positions a formed corrugation in the lower die assembly prior to the corrugating operation is resiliently mounted on a block 79 slidable in the upper die plate 93. The corrugated strip extends downwardly from the top of a slot 75 in the lower die block through a shoot 81. As the head 72 moves upwardly after forming a corrugation the strip is moved upwardly by a spring-loaded stripper assembly 74 and a spring-loaded stripper bar 80 extending above the strip prevents the strip from moving upwardly with the upper die assembly. From the dies the corrugated strip moves at an angle (Fig. 3) to its previous feed direction through another guide and feeler unit 82 to a cut-off unit 44 for cutting the strip into predetermined lengths. Shearing.-The cut-off unit comprises a stationary lower cutter blade 100 and a movable spring-loaded upper blade 102 operated by a slidable spring-loaded bar 106, the anvil 108 of which is moved into line with an adjustable stud 98 mounted in a bracket on the press head. In operation, the apparatus is started by swinging a lever 110 downwardly to engage a clutch between the flywheel pulley 116 and the press shaft 118. Operation of the lever 110 also raises a plunger 122 which engages a latch 124 (Fig. 16) and thus holds the lever 110 in the operating position. To stop the press the latch bar is withdrawn by a solenoid assembly 128. An electrical timer is incorporated in the strip feed to start and operate the electrical motor for a predetermined number of seconds for each intermittent unreeling operation. When the loop passing through the guide 36 becomes taut the strip touches an electrical contact 109x to energize the relay which operates the motor. The strip is fed after each corrugation has been formed and the corrugation last formed is positioned beneath the pilot blade 66. Finally the strip is cut into predetermined lengths. Making heat exchangers.-The corrugated strip is wound into a tube 4 (Fig. 14) and the assembly inserted into a tube 2, whereupon the tube 4 is expanded to place the fin structure under radial compression.