Pressing method, in particular for obtaining hydraulic cylinders and high-pressure filters

A pressing method for obtaining cylinders and filters comprising:

• providing a semi-finished product of cylindrical shape having a first end with a blind hole therein, wherein the semi-finished product has been subjected to a first chemical surface treatment;
• inserting a first punch into and over part of the depth of the blind hole for defining a first machined zone in the hole, removing the first punch;
• inserting a second, reversed profile punch in the hole for performing a first sizing of the first machined zone thereby defining a second machined zone;
• removing the second punch;
• applying a second chemical surface treatment of the semi-finished product after the first sizing;
• applying a pressing step in the second machined zone by inserting a third punch in the hole for defining a third machined zone with a selected thickness for the semi-finished product;
• removing the third punch;
• performing a second sizing of the third-machined zone by inserting a fourth punch in the hole for defining a fourth flat contact zone in the third machined zone for producing the cylinder, and removing the fourth punch.