Patent GB-652367-A (GB)
Title: Improvements in or relating to apparatus for shaping and curing pneumatic tires
IPC: B29D30/06
Filed: 1947-06-19
Abstract: 652,367. Tyre moulding and vulcanizing presses. McNEIL MACHINE & ENGINEERING CO. June 19, 1947, No. 16196. Convention date, July 25, 1946. [Class 87 (ii)] A tyre moulding and vulcanizing press comprises two relatively movable platens 1, 28 to which are secured a pair of co-operating mould sections 31, 30, and a tubular inflatable diaphragm D which acts as a curing bag and which is secured at its edges to a pair of supporting discs 65, 66, disposed between the mould sections. One or both of the platens is movable to open and close the press. On opening the press after moulding a tyre, the tyre remains temporarily in one mould section, both discs then move away from this section to free the tyre therefrom and finally the discs move apart to strip the diaphragm from the tyre which is independently supported during this stripping action. As shown, the platens &c. are superimposed and the upper are only is movable. General construction, (Figs. 1 and 10). A bed plate or lower platen 1 is supported above base plates 2 by four webs 3 through which heavy I-beams 5 extend from side to side of the press. Reinforcements 18 on the outer webs 3 provide bearings for main shafts 16, 17, also supported by the inner webs 3. The shafts carry large gears 20, each carrying a crank-pin 24 projecting through cover-plates at the sides of the press and on which are journalled the lower ends of toggle links 25. The upper ends of the links are pivoted to the ends of the crosshead 26 which carries an upper platen 28 adjustable in the manner described in Specification 586,281. The shaft 16 also carries a cam 34, crank 114, and disc 140, the shaft 17, another cam 34 and crank 112. The gears 20 are driven from a reversible motor 8 at the back of the press through reduction gears 12, 14, 15. The platens 1, 28 carry mould sections 30, 31 which may be cored out for the circulation of steam, as shown, or housed in steam boxes. Mould opening and closing, (Figs. 1, 10, 16). The motor 8 drives the gears 20 in the direction of the arrow a, Fig. 1, through approximately 210 degrees to lift the crosshead 26 with the platen 28 and mould section 31 secured thereto. For the first part of the lift the motion of the cross-head is maintained vertical without tilting by means of links 58, rigidly secured at one end to the cross-head, while their other ends work in guides 51 and are raised initially at the same rate as the cross-head by links 48, Fig. 16, pivoted at 47 to the ends of arms 42 which swing upwards about pivots 40 by the cams 34. After a 90 degrees rotation of the gears 20 the cams 34 allow the arms 42 and hence the links 48 to drop, causing the links 58 to pull the cross-head backwards and at the same time tilting the front parts of the upper platen and mould section 31 upwards. Reversal of the motor reverses the motion, the latter part of the closing movement of the upper mould section being vertical. It is stated that the mould opening and closing may alternatively be entirely a straight-line motion. Diaphragm disc mechanism, (Figs. 10 and 13), and general operation.-The upper disc 65 to which the upper beaded edge of the tubular diaphragm is secured by a clamping ring 68 is mounted for vertical movement on the end of a rod 79, the lower end of which is adjustably mounted in a block 84 sliding on a pair of parallel rods 86. The ends 86 are themselves slidable in a block 82 secured to the platen 1, and in guides 88 secured by cross rods to the I-beams 5. The rods 86 are received in half bearings in the block 84 and half bearings 96, urged against the rods by springs 99. The various bearing surfaces are lined with friction material. The rods 86 carry at their upper ends the lower disc 66 to which the lower beaded edge of the diaphragm is secured by a clamping ring 74. The clamping rings 68 and 74 are adapted to seat in recesses in the upper and lower mould sections 31, 30 when the mould is closed and ring 74 has a projecting rim 75 which engages under the lower head of a tyre in the press. A cam-plate 102, Fig. 10, is secured to the block 84 and a cam-plate 104 to the rods 86. When the press is opened from the closed position shown in Figs. 1 and 10, after the upper mould section has moved a short distance a roller 110 on the crank 112 engages beneath the cam-plate 102 to lift the block 84 and hence the rod 79 and upper disc 65. The lower disc 66 is also lifted, by the friction coupling between the block 84 and rods 86, the moulded tyre being stripped from the lower mould by the rim 75 on the lower ring. A roller 115 on the crank 114 then engages above the cam 104 to force the lower disc down, the upper disc meanwhile continuing to move up until the ring 74 is seated in the lower mould section and the diaphragm is stripped from the tyre, which is meanwhile supported by arms which have moved in from the side beneath the tyre (see below). The final position of the discs 65, 66, diaphragm D, &c, is as shown at the right in Fig. 3. The moulded tyre T is removed and a fresh tyre band B slipped over the diaphragm and seated on the rim 75 of the ring 74. On closing the press the cranks 112, 114 return without affecting the cams 102, 104 and the upper disc 65 is returned to its Fig. 1 position by the descent of the upper mould section 31. Air trapped in the diaphragm causes it to bulge out to fit into the tyre which is shaped to approximately to its final form by pressing between the mould sections. After closure of the press hot pressure fluid is circulated in the diaphragm through conduits 83 screwed into bosses 71 upstanding from the block 82, apertures therein communicating with apertures in the lower ring 66. Instead of two conduits 83 one only may be supplied for admission of pressure fluid. Tyre supporting arms, (Fig. 11). These extend across the press at front and back and are carried on the ends of arms 121 pivoted to the press frame at 120. The arms 121 are rotated about the pivots 120 by movement of the rounded ends of two-armed levers 130 through friction drives 126. The other ends of the levers 130, which are pivoted at 133 and 38, carry rollers 131 urged by springs against cams 134, 135 secured to either side of the crank 112 on the shaft 17. The cams 134, 135 are arranged to move the tyre supporting arms into the space between the mould sections after the tyre has been stripped from the lower mould to' support the tyre during and after the stripping of the diaphragm, and to move out again as the press begins to close. Operating mechanism for control gear.- Control gear for the vulcanizing cycle is contained in a box 9, Fig. 13, and is not described. The box 9 carries two projecting switches 9a, 9b separated vertically and horizontally. Depression of switch 9a causes the motor 8 to stop and depression of the switch 9b initiates the automatic timing gear which opens the press after the end of a predetermined time and controls the flow of pressure fluid to the diaphragm. The switches are operated by rollers on the ends of three arms projecting radially from the disc 140. When the press is closed both switches are depressed. When the press is fully open switch 9a is depressed. This switch is also depressed to stop the press when the press is closing, when the upper press section is about to contact the upper disc 65, to allow the operator to check that all is well. The press may also stop at the corresponding position in the opening movement. The stoppings at the intermediate position may, however, be eliminated. The press is started from the open and intermediate positions by a manual switch and is automatically opened at the end of the moulding cycle. Specification 416,268 also is referred to.