Patent GB-528264-A (GB)
Title: Improvements in methods and apparatus for splicing rubber articles
Filed: 1939-05-02
Abstract: 528,264. Cutting-machines. WING FOOT CORPORATION. May 2, 1939, No. 13065. Convention date, Feb. 4. [Class 31 (i)] [Also in Groups V and XXXIV] Unvulcanized indiarubber inner tubes and treads for pneumatic tyres are spliced by flattening them, cutting off the ends by means of heated knives with oblique or off-set cuts so as to form non-parallel cut surfaces, and finally pressing the freshly cut ends together to form a joint, sufficient pressure preferably being exerted to form small fins of excess material around the joint. Fig. 1 shows in elevation a machine for carrying out the process. The ends of the tube or tread T3, which is arranged over a support 150, are held between pivoted clamping members 15, 16, and 17, 18, with the extremities disposed over a vertically movable anvil 19, the lower elements of the clamping members being mounted on carriages 30, 31 capable of movement towards or away from one another on guides 32, 33. The hinged upper members may be constructed with yieldable plates surrounding inflatable cores as described in Specification 418,185, [Group XXIII]. The first step of the cutting operation is shown in Fig. 5 where the descending electrically heated knives 20 have penetrated part way through the upper portion of a flattened tube ; following this preliminary incision the carriages are caused to separate so that the completed cuts are of the off-set form shown in Fig. 7. The tacky cutsurfaces are now united by approaching together the clamping members, the knives and the anvil having moved out of the way. The surfaces unite first along the lower edges and then progressively throughout the section, avoiding the entrapping of air between the parts, and preferably so that fins 24, Fig. 11, are formed surrounding the joint; these fins become merged and disappear during the subsequent vulcanization of the spliced tubes in a mould. The machine is operated by compressed air through a system of pressure cylinders and valves actuated in timed sequence from cams 101-105, Fig. 4, on a shaft driven through gearing from an electric motor 96 housed in the lower part of the machine, the cams actuating plunger rods to operate the valves 111-115. Thus the admission of air to one or other end of cylinders 41, 42 opens or closes the upper clamping members 16, 18. Cylinder 56 similarly controls the movement of the carriages 30, 31, which are attached to horizontal rack bars and moved by pinions which rotate with gears in engagement with a vertical rack bar 54 connected to the piston rod, and the anvil 19 is mounted on the upper end of the piston rod 59 of cylinder 60. The knives are mounted on a vertically guided slide 62 secured to the lower end of piston rod 65 of cylinder 66 and carrying also a pair of rods 74 to which is secured a cross-arm 73 carrying an abutment 70 and an extension 71 adapted to actuate a switch 72. The piston rod 69 of a cylinder 67 mounted on a fixed cross-bar 68 is disposed in the path of the abutment 70 so that the downward movement of the knives on the admission of air into the upper part of cylinder 66 is halted when the abutment 70 contacts with the end of piston rod 69, affording the cutting position shown in Fig. 5. The closing of the switch by the extension 71 actuates a valve to release the pressure in cylinder 67, permitting the completion of the cutting operation when the clamping members have separated. The machine is started by the closing of switches 153, 154 arranged in series by operating the handles 151, 152. The kicking in of a safety bar 155 stops the machine and returns the parts to inoperative position. Specification 387,793, and U.S.A. Specification 2,024,578, also are referred to.