Patent GB-656148-A (GB)
Title: Machines for making radio tubes and like devices
IPC: H01J5/24
Filed: 1947-12-23
Abstract: 656,148. Machines for sealing radio tubes &c. SYLVANIA ELECTRIC PRODUCTS, Inc. Dec. 23, 1947, No. 34081. Convention date, Dec. 24, 1946. [Class 39(ii)] A machine for making a seal between a glass stem and a coaxially assembled glass or metal shell to form the envelope of a radio tube or the like, is provided with a vertical chuck for supporting the stem from below, and a shell-gripping chuck co-axial with the stem chuck and provided with jaws which grip the shell above the stem and extend normally from below the stem, operating mechanism for opening and closing both chucks being located below the shell and stem assembly, with a cam for shifting one chuck relative to the other to render the stem chuck accessible for loading and unloading. The chucks are mounted on a turret which is indexed in known manner through a series of stations at most of which the chucks are rotated about their own axis. Each work-receiving head comprises a tubular member 18 rotatable within a bush 20 in the turret and secured at its bottom end to a clutch 12 which can be engaged with a pinion 14 driven by an endless chain 16 and rotatable upon the member 18. A tube 31 slidable vertically within the sleeve tube 18 supports the header of the radio tube, comprising generally a glass disc H with an axial exhausting tube T arranged to be gripped by the stem chuck, external contact pins, and a mount assembly.  Shell chuck.-Three jaws 10 comprising the shell chuck, are each supported by one of three radial projections on a collar 40 clamped to the upper end of the rotary sleeve tube 18 by a set-screw. Two of the jaws 10 have two points at which they contact' a shell S, while the third has a single point contact. The integral supporting limbs of the jaws may be bowed as shown, and, in order to reduce the barrier they interpose between the burners B and the parts to be sealed, the mid-portions of the limbs are streamlined. The lower end of each limb is held by a screw 34 within a slotted block 32 which is mounted on a pair of leaf springs 38 supported by one of the radial projections on the collar 40. The leaf springs 38 provide parallel linkages which prevent pivotal swinging of the jaws 10 and ensure a substantially horizontal shifting of the blocks 32 and jaws. Operation of a jaw is effected through a lever 44 pivoted in a slot in the radial projection on collar 40, and engaging at its upper end a lug 46 on the underside of block 32, movement of the lever being produced by thrust from an arm 50 engaging its lower end. The three arms 50 associated with the respective jaws 10 are pivoted on a ring 52 which is keyed to the rotatable sleeve member 18 and slidable thereon, an upward sliding movement to effect opening of the jaws 10 being produced by a yoke 60 which engages a peripheral groove in the ring and is moved upwardly by the bottom end 66 of a vertical rod 62 running on a cam track. Such a track is provided at the loading and unloading positions, otherwise the ring 52 is pressed downwardly by a compression spring 54 and the jaws 10 are closed upon a shell S. Stem chuck and support.-The stem chuck has three jaws 81, Figs. 1 and 8, which are moved inwardly through vertical slots near the upper end of tube 31 and grip the exhausting tube T, the inward movement being limited by upper and lower lugs 82 on the jaw. Movement of each jaw is effected by an associated toggle member 98 seated in an annular cup at the upper end of a sleeve 86 subjected to upward pressure by a helical spring 90, the resulting movement of the sleeve being limited by an adaptor 72 secured at the top of the innermost tube 31 by a set-screw 74 and formed with a tubular baffle 80 functioning to shield the exhausting tube from hot gases, in the manner described in Specification 632,746. The sleeve 86 and tube 31 are keyed together by a longitudinal key which is slidable relative to a longer keyway in the tube. The gripping jaws 81 grip the exhausting tube T during the time that the cam follower 110 at the lower end of tube 31 is on the low portion of the annular controlling cam 112, but when the tube 31 is raised beyond a predetermined amount a relative longitudinal movement of sleeve 86 is produced by the spring 90, whereby the grippers are released to allow removal of a fused envelope and insertion of a new header H with its exhausting tube T at the next consecutive station. Fig. 9 shows the contours of the stationary cam tracks along which the cam followers 66, 110 are moved intermittently, there being sixteen work-supporting spindles around the turret. Various burners act on the edges of shell and header during travel between the fifth and twelfth stations. Preheating flames may be directed on the underside of the header to minimize internal strains. The edges of the shell S and header H are fused on arrival at the thirteenth station and are there pressed together by a cam operated lever 114 acting on the lower end of camfollower 110, the seal being stretched by a small amount when the latter member is allowed to drop. Cooling takes place during transit to the removal station.