GB740922A - Methods and apparatus for testing the adhesive properties of sizing liquids and the like, for ascertaining their condition during preparation - Google Patents

Abstract

740,922. Testing adhesive properties of liquids. SUCKER GES., GEB. May 8, 1953, [May 8 1952; Feb. 4, 1953], No. 12955/53. Class 106 (2). A method of testing the adhesive properties of sizing liquids or the like, comprises wetting two surfaces of a testing instrument with the liquid, pressing the wetted surfaces together, and then measuring the force required to pull the surfaces apart. Two pads 3, 4, Fig. 1, are mounted on arms 1, 2 pivoted at 6, the arm 1 having a cross-arm 9, 10 carrying two slidable weights 11, 12 interconnected by a rod 13. The weights are also joined by a band 14 passing round a hand-actuated roller 15 for moving the weights along the cross-arm 9, 10. Displacement of the weights to the right causes the arms to open. The instrument is then immersed into the liquid under test and the weights deflected to the extreme left-hand position to cause the pads 3, 4 to close under known pressure. By slowly moving the weights to the right a parting force is created and then increased. A finger 17 on the weight 12 indicates on a scale 18 the loading at the instant that the parting force overcomes the adhesive action of the liquid. A thermometer 22 is included. Behind the scale 18 is a recording strip (shown dotted) on which bears a stylus carried by the weight 12. At the instant of separation of the pads, a kink is made in the line drawn by the stylus. In Fig. 3, the surfaces of the pads 23, 25 are part-cylindrical. An arm 26, swing- able about the axis of the surfaces, carries a brush 28. A pinion on the brush engages a stationary toothed quadrant 30 so that on swinging the lever 26 the brush is rotated about its axis to clean the pads 23, 25. The pad 25 is secured to a bellows seal 32. A rod 33 connected to the pad 25 has a collar 34 and is surrounded by upper and lower helical springs 36, 35 separated by a perforated plug 37 fitted in a threaded tube 38. The upper end of the tube 38 carries a bracket 39 on which a pointer arm 40 is pivoted. The rod 33 is connected to the arm 40. A worm-wheel 41 engages the thread of the tube 38, the worm wheel being rotatable in a fixed bearing 42 and being driven by a worm 43 coupled to an electric motor 44. A recording drum 45 is acted on by the free end of the arm 40. In the range of the arm 40 is a vertically adjustable switch 46. A potentiometer 48 is wiped by a contact 49 on the arm 40. On the tube 38 is a switch arm 51 which, on reaching upper or lower limiting positions, actuates a change-over switch 52 to reverse the rotation of the motor 44. The pads 23, 25 are in a chamber 53 having inlet and outlet valves 54, 55 and a thermometer. In operation, the motor 44 is switched on, whereupon the tube 38 rises and moves the pad 25 and the bellows 32 upwards, causing the liquid to be tested to be drawn through the valve 54 into the chamber 53. On reaching an upper position the switch 52 is actuated and the pad 25 and bellows 32 descend, most of the liquid in the chamber 53 being forced out through the valve 55 owing to the increase in volume of the bellows 32. The tube 38 continues its downward movement after the pads 23, 25 are in contact so that the spring 35 commences to apply a pressure to the pad 25. When the tube 38 reaches a lowermost position, the switch 52 is again actuated to reverse the motor 44. The tube 38 commences to move upwards but due to the adhesive action of the liquid between the pads 23, 25 the pad 23 and the bellows 32 do not immediately move. Upward movement of the tube 38 compresses the spring 36 to apply a gradually increasing upward force to the pad 23. When the compressive loading exceeds the adhesive force between the pads 23, 25 the pads separate and the rod 33 moves upwards to deflect the arm 40 on the record drum to a position which indicates the force required to separate the pads. The bellows 32 move upwards with the rod 33 to draw fresh liquid into the chamber 53 and the brush 28 is used to clean the pads. On the tube reaching an upper position the motor 44 is again reversed and the operation repeated. If during the upward movement of the tube 38 the free end of the arm 40 descends far enough to strike the switch 46, which is set in a position corresponding to an adhesive force of the desired value, a signal or automatic control is actuated by the switch. In a third embodiment the pads are immersed in the liquid to be tested and are drawn together by electromagnetic means. Thereafter the electromagnetic means is de-energized and compressed air is slowly applied to a piston and cylinder arrangement adapted to force the plates apart.