# US 4,395,894 A · Automatic closing machine for sheet metal joints > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,395,894 A - Document ID: US4395894A - Status: Granted - Kind: A - Application number: 06/291,235 - Filed: 1981-08-10 - Granted: 1983-08-02 - Earliest claimed: 1981-08-10 - Inventors: Allan F. McCorvey - Web page: https://patentgrep.com/patent/US4395894A ## CPC - B21D 39/02: of sheet metal by folding, e.g. connecting edges of a sheet to form a cylinder - Y10T 29/49893: Peripheral joining of opposed mirror image parts to form a hollow body - Y10T 29/49924: of parallel side-by-side elongated members - Y10T 29/53791: Edge binding - B21D: WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL (working or processing of wire B21F) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract An automatic closing machine for sheet metal joints in sheet metal ducts or the like consists of a powered rotary hammer for continuous application of a hammering force to the edge portion of a joint to be formed to fold such edge into a closed joint. A supporting frame with a vertically adjustable support permits varying the relative vertical spacing of the edge of the duct and the rotary hammer. Stops locate the duct longitudinally to set the length of the joint relative to the location of the end connecting edges of the duct. Pneumatic clamps secure the duct accurately for forming the joint by the rotary hammer. A track supports the rotary hammer for longitudinal movement and an automatic traversing mechanism moves the rotary hammer therealong. The traversing mechanism automatically moves the rotary hammer back and forth along the track. The vertical adjustment locates the edge of the unformed duct properly relative to the path of movement of the rotary hammer for any selected duct size. Likewise, the traversing mechanism controls may vary the distance of movement of the rotary hammer for any selected duct length. The apparatus is satisfactory for forming both one-piece duct joints and two-piece duct joints. ## Claims ### Claim 1 An automatic machine for closing Pittsburgh Lock joints in the corners of sheet metal conduits of square or rectangular cross-section comprising a supporting frame, a powered rotary hammer, means supporting said rotary hammer on said frame for reciprocal longitudinal movement thereon, motor means for moving said rotary hammer reciprocally on said supporting means for a predetermined distance, said frame including a portion extending longitudinally thereof and providing a vertically extending clamping surface positioned along and beneath the path of movement of said rotary hammer on said hammer supporting means, means for clamping one wall of an unformed sheet metal conduit of square or rectangular cross-section, having an unformed Pittsburgh Lock joint at a corner thereof, against said clamping surface to position said wall with the unbent portion of said joint vertically beneath said hammer path of movement and another wall of said conduit surrounding said clamping means and having an edge portion formed to mate with said unbent joint portion so that said reciprocal and rotary movement of said hammer is effective to bend said unbent portion into a tightly closed Pittsburgh Lock joint. ### Claim 2 (depends on 1) An automatic closing machine for sheet metal joints according to claim 1 in which said rotary hammer comprises a rotary shaft, motor means for rotating said shaft, a disc shaped supporting member supported on said shaft for rotation thereby, a plurality of hammer posts supported in a circular pattern on said disc and operable upon rotation to engage the sheet metal edge with continuous and repeated hammer blows, and said rotary hammer being supported at an inclined angle such that rotary movement of the respective hammer posts will be upward and away from the joint being formed after bending the sheet metal to form said joint. ### Claim 3 (depends on 1) An automatic closing machine for sheet metal joints according to claim 1 in which said frame includes means for supporting said sheet metal wall portion in a selected vertical spacing from said hammer path of movement, and means for adjusting said supporting means to adjust the position of said shet metal wall portion relative to the path of movement of said hammer supporting means to accomodate sheet metal ducts of different sizes. ### Claim 4 (depends on 3) An automatic closing machine for sheet metal joints according to claim 3 in which said frame includes a supporting table portion for the sheet metal duct in which a joint is to be closed, and means for adjusting the position of said supporting table vertically relative to said rotary hammer supporting means. ### Claim 5 (depends on 4) An automatic closing machine for sheet metal joints according to claim 4 in which said rotary hammer supporting means comprises a track supported on and extending longitudinally of said frame and supporting said rotary hammer for movement thereon. ### Claim 6 (depends on 5) An automatic closing machine for sheet metal joints according to claim 5 in which said supporting table adjusting means comprises a scissors type support for said table, and motor means for operating said scissors type support to move said supporting table to a predetermined vertical position relative to said rotary hammer supporting track and said vertical clamping surface. ### Claim 7 (depends on 1) An automatic closing machine for sheet metal joints according to claim 1 in which said frame includes stop means for positioning the cooperating edge portions forming said Pittsburgh Lock joint in a predetermined position along said vertical clamping surface relative to the path of reciprocal movement of said rotary hammer to assure accurate closing of said joint in relation to the ends of the duct. ### Claim 8 (depends on 7) An automatic closing machine for sheet metal joints according to claim 7 in which said stop means comprises a fixed stop at one end and a spring loaded stop at the other end of said vertical supporting surface operable to hold said conduit one wall portion therebetween. ### Claim 9 (depends on 1) An automatic closing machine for sheet metal joints according to claim 1 in which said motor means for reciprocally moving said rotary hammer includes adjustable means for varying the length of the path of movement of said rotary hammer. ### Claim 10 (depends on 1) An automatic closing machine for sheet metal joints according to claim 1 in which said sheet metal supporting means comprises power operated clamping means movable relative to said vertical clamping surface to clamp said one sheet matal wall therebetween. ### Claim 11 (depends on 1) An automatic closing machine for sheet metal joints according to claim 1 in which said motor means and the power for said rotary hammer comprise fluid operated motors. ### Claim 12 (depends on 1) An automatic closing machine for sheet metal joints according to claim 1 in which said motor means and the power for said rotary hammer comprise electric motors. ### Claim 13 (depends on 1) An automatic closing machine for sheet metal joints according to claim 1 in which said rotary hammer comprises a rotary shaft, motor means for rotating said shaft, a disc shaped supporting member supported on said shaft for rotation thereby, a plurality of hammer posts supported in a circular pattern on said disc and operable upon rotation to engage the sheet metal edge with continuous and repeated hammer blows, said rotary hammer being supported at an inclined angle such that rotary movement of the respective hammer posts will be upward and away from the joint being formed after bending the sheet metal to form said joint, said frame includes means for supporting said sheet metal wall portion in a selected vertical spacing from said hammer path of movement, and means for adjusting said supporting means to adjust the position of said shet metal wall portion relative to the path of movement of said hammer supporting means to accomodate sheet metal ducts of different sizes, and said frame includes stop means for positioning sheet metal ducts, on which joints are to be closed, in a predetermined position along said vertical clamping surface relative to the path of reciprocal movement of said rotary hammer to assure accurate closing of said joint in relation to the ends of the duct. ### Claim 14 (depends on 13) An automatic closing machine for sheet metal joints according to claim 13 in which said motor means for reciprocally moving said rotary hammer includes adjustable means for varying the length of the path of movement of said rotary hammer, and said sheet metal supporting means comprises power operated clamping means movable relative to said vertical clamping surface to clamp said one sheet matal wall therebetween. ### Claim 15 (depends on 14) An automatic closing machine for sheet metal joints according to claim 14 in which said frame includes a supporting table portion for the sheet metal duct in which a joint is to be closed, means for adjusting the position of said supporting table vertically relative to said rotary hammer supporting means, and said rotary hammer supporting means comprises a track supported on and extending longitudinally of said frame and supporting said rotary hammer for movement thereon. ### Claim 16 (depends on 15) An automatic closing machine for sheet metal joints according to claim 15 in which said supporting table adjusting means comprises a scissors type support for said table, and motor means for operating said scissors type support to move said supporting table to a predetermined vertical position relative to said rotary hammer supporting track.