Patent GB-385476-A (GB)
Title: Improvements in machines for testing cans for airtightness
IPC: G01M3/32
Filed: 1932-03-05
Abstract: 385,476. Testing efficiency of cans. ARMSTRONG, J. J. V., 12, Church Street, Liverpool.-(Continental Can Co., Inc. ; 100, East 42nd Street, New York, U.S.A.) March 5, 1932, No. 6661. [Class 106 (ii).] A machine for testing cans for leaks comprises a series of travelling testing units, a separating mechanism associated therewith through which all the cans being tested are discharged, said mechanism including a series of travelling suction cups operating in succession on the cans being tested, and means controlled by the testing units for causing said cups to discharge selectively the leaky cans at a different point from the discharge of the perfect cans. Each testing unit is provided with a chamber 5 in which the can C to be tested is placed on a support 6 and lowered into the chamber which is closed by a cover 7, a pad 8 on the underside of which closes both the chamber and the can. Air under pressure is then admitted through the pipe 9 and if the can is leaky the pressure in the chamber 5 will rise above atmospheric. Associated with each unit is a U-tube, the transparent leg 13, the reservoir leg 11 and the bend 21 of which contain water. The leg 13 has two electrical contacts 22, 23 the latter of which is adjustable, and normally the height of water is such that water covers the break between the contacts. The leg 13 is connected to the chamber 5 while the leg 11 is open to the atmosphere. On the pressure rising in the chamber 5 the water in the tube 13 will be forced down so that the electric circuit containing the contacts 22, 23 is broken. The contact 22 is joined to a contact 27 moving with the unit. If the can is sound the circuit is unbroken at contacts 22, 23 and when a fixed contact 28 is engaged by the contact 27 a solenoid 33 is energized to move a pivoted catch 29 from the position shown in dotted lines to the full line position shown. When the can leaks the trip remains in the dotted line position. The separating mechanism is mounted on a standard and comprises a turret 39 provided with suction devices 46 .. 51. Each device comprises a pliable cup 52 attached to a tube 53 adjustably secured to the turret. A port 54 connects each cup with a recess at the inner end of the tube which communicates with a vertical port 56, 57. A second parallel port 58 is spaced 45‹ from the port 57 and is connected at the bottom thereto. In the port 57 is a valve 60. Extending downward into the turret is a tapered head 61 which is stationary and is provided with a stem 63 with a bore 69 which connects to a vacuum pipe 70. A radial port 71 in the head connects with a circumferential port 72 with which a horizontal port 73 at times makes connection. A port 74 at the top of the port 58 also at times connects with the port 72. The head 61 is provided with a port 75 which connects with a radial port 76 leading to a recess 77 in the face of the head. This port 75 communicates with the atmosphere. The ports 73, 74 during each rotation of the turret will thus be vented to the atmosphere via the recess 77. Each valve 60 has an operating head 78 provided with arms 79, 80. Located in the path of travel of the valve head is the bent-over end 82 of an arm 81. A spring 83 surrounds the stem of each valve. The turret rotates clockwise, as shown in Fig. 1, and prior to the valve passing the trip lever 29, the valve engages the end 82 of arm 81 and is turned to the " open " position shown in Fig. 3. If the can is sound, the trip lever has been moved and the valve remains open. In this position both ports 57, 58 are wide open and as they reach the port 72 are connected to the vacuum. The cup will therefore engage the can which is conveyed out of the testing unit across the supporting plate 38. This has an opening 84, but the suction is sufficient to carry the can across this opening to the position C<1>. When the port 73 reaches the recess 77 the suction will be open to the atmosphere and the can is discharged between guides 85, 85. If the can is leaky the trip is not moved and is engaged by the valve head which is turned to the position shown in broken lines, Fig. 3. The only vacuum created then will be through port 58 and this is sufficient to carry the can until over the port 84 when the port 74 registers with recess 77 and the cup is connected to atmosphere, the can being dropped through the opening 84. Specification 333,363, [Class 106 (ii), Dynamometers &c.], is referred to.