| 摘要 |
797,164. Rubber compression springs. NATIONAL MALLEABLE & STEEL CASTINGS CO. May 24, 1956 [June 6, 1955], No. 16081/56. Drawings to Specification. Class 108(3) A method of making a cushioning unit having a capacity and a size within predetermined tolerances, from a group of resilient pads of rubber-like material, comprises the steps of grouping an established number of the pads, subjecting them to a predetermined compressive force to induce a permanent set in the resilient material of the pads, releasing the force, determining the capacity and size of the unit, and in the event that the capacity or size is above or below the predetermined tolerances, substituting one or more pads of a different thickness or hardness, as necessary, to bring the capacity and size within the predetermined tolerances. The force may be applied as a single force of about 85 per cent of the design load for the pads of the unit at the latter's maximum rated travel. Alternatively the force may be applied in the form of three to five successive loads in fairly rapid order, each being about one-half of the design load for the pads. The unit is then allowed to set for a period of from 48 to 72 hrs. The capacity and size of the unit is determined by either recompressing the unit to a given overall length and measuring the load required, or by recompressing the unit by a given force and measuring the height of the unit under this force. The pads may be of the construction described in Specification 686,211. Where it is necessary to substitute fresh pads in order to adjust the capacity and size of the unit, the added pads should previously have been subjected to a compressive force to take up permanent set. While the unit is under the set-inducing force the edges of the pads are inspected for any defects which may occur. The pads should be removed from the rubber curing moulds for at least 24 hours before the set-inducing force is applied. |
