MANUFACTURERS OF DIE CUSHION EQUIPMENT
SPARES SUPPLY ONLY OR SUPPLY AND FIT
Die Cushion Equipment is generally a means of providing CONTROLLED RESISTANCE by means of which a blank is automatically held in a grip; not to firm and not too light; to enable simple tools in a Press to Draw STRONG, SMOOTH shells, raisings or pressings, at a higher rate of production because single action presses are used in place of double action; and double action are used in place of triple action presses.
Proir to the introduction of Die Cushion Equipment, springs and/or rubber buffers were often used, but best results could not be obtained, as it is impossible by these means to provide enough pressure at the beginning of the press stroke without developing too much at the end of the stroke.
When deep draws are made with increasing pressure, especially on light gauge material, the metal will either wrinkle at the beginning under the light pressure, or be held so tightly by the heavy pressure towards the end of the draw that the metal breaks.
When using Die Cushion Equipment on say a single action press, the tools are inverted, i.e. the die is the top tool and the punch is the bottom tool. A draw ring or pressure ring, surrounding the punch, is supported on draw pins or pressure pins, which pass down through clearance holes in the press bed or bolster, to contact with the top pad of the Die Cushion Equipment. This top pad connected with the piston or pistons of the die cushion unit, which is suspended under the bed of the press.
It is obvious, if the cylinders in the Die Cushion Unit are filled with air, water, oil or other suitable fluid under pressure, that the piston, top pad and draw pins will be forced upwards, carrying the draw ring with them.
The afore-mentioned automatic grip is thus provided, the blank being placed between the draw ring and the die, when the slide of the press descends, the blank is gripped. Now as the pressure per square inch of the fluid member is accurately and automatically controlled, a grip is provided on the blank which is not so firm that the metal bursts or tears when being drawn over the punch, and not so light that the metal puckers in the process. The pressure is controlled by means of a Worson Automatic Regulating Valve, which automatically holds the correct pressure required. The pressure is read on a gauge and may be recorded on the tools for future reference, when tools may be set up again without experiment. Drawing tools may therefore be set up in the same time approximately as blanking tools, as the blank is held at a pre determined pressure, and not at a predetermined point of the stroke. This fact avoids many hours spent in adjusting exactly a mechanical draw ring, and those strains on the press caused by variation in blank thickness.
The Worson system of Pneumatic operation ensures precise control
Three systems are generally employed, namely: Hydraulic, Hydro-Pneumatic and Pneumatic. These are provided to deal with very heavy work, and general work, respectively. With the first system, we confine oil or water in a cylinder or Cushion Unit. The slide of the press, in its decent, forces this liquid out of the cylinder through a variable orifice valve, which is mechanically controlled.
With the Hydro-Pneumatic system, the oil or water confined in the cylinder or Cushion Unit is forced through a pneumatically operated variable orifice valve into a receiver or tank partly filled with oil or water and partly by compressed air. This system permits much more accurate pressure control than the full Hydraulic System.
In the third system – Pneumatic – we have only compressed air in the cylinder or Cushion Unit, pipeline and receiver or tank. This last system provides the most accurate and precise means of producing the required CLOSELY CONTROLLED RESISTANCE. The control is so accurate that the most delicate materials can be drawn satisfactorily, and parts are produced which would be quite impossible by other means. On the other hand, strong smooth pressings are produced on the same equipment up to the full capacity of the press. It is therefore obvious that the Pneumatic system is the most UNIVERSAL system. This is borne out by the fact that Pneumatic Die Cushion Equipment is used in the majority of the large and small press shops worldwide, and is recommended and sold by every English press manufacturer.
Worson Die Cushions ensure maximum economy and efficiency
During the operation of the press, it must be appreciated that Worson Die Cushion Equipment uses no air.
The air displaced by the movement of the pistons in the Cushion Unit is transferred by means of a large diameter pipeline to and from the receiver, which is of sufficient capacity to avoid any harmful increase in pressure.
Therefore a small compressor will look after a long line of Worson Die Cushion Equipments. Further advantages are the facts that the pressings are ejected up to the full capacity of the Cushion Unit, whilst piercing, raising, ribbing, coining and clipping may be performed in the same stroke as the draw, right up to the maximum capacity of the Cushion Unit.
Worson Die Cushion Equipments are made even more universal by the provision of 2, 3, 4 or more top pads, enabling as many different pressures to be obtained over the surface of one or more dies.
Simple or combined sets as above may have a simple or fully universal and automatic control fitted
Please contact us with your requirments for a free quotation.