SEALS FOR LARGE PNEUMATIC CONSTRUCTIONS

Scenario

Working on large diameters can lead to problems with manufacturing precision large tolerances and long lead times.

Challenge

In machinery designed to produce tires for special machines, the definition of rotary joint sealing systems is of paramount importance. For this reason, a manufacturer, our customer, involved us in the design and implementation of a customized seal. The seal had to take into account the high speeds and, consequently, the critical temperatures reached in the joint, but also the large dimensions of the seals that made it necessary to recover the wide manufacturing tolerances of both the seats and the seal.

Solution

First, the technical team analyzed the operating conditions of the joint, which involved a seal with a diameter of 900 mm:

• Average: dry air
• Movement: rotary
• SEAL: ON Ø900 mm STEEL
• Speed: 0.5 m/s
• Pressure: 10 bar
• Temperature: max. 80°c

For making large gaskets, in this case exceeding 700mm, the high weight of the semi-finished product led our technicians to use a vertical axis machining center.

Thanks to the experience of its technicians and turners, ATP is able to reduce production tolerances and obtain functionally very precise seals, even for large diameters. The use of FEM analysis, a tool routinely used in ATP’s engineering and R&D department, makes it possible to perform preliminary application studies, comparing theoretical results on different profiles and defining which seal will maintain the best sealing efficiency and effectiveness.

In particular the choice fell on the Bi-material Seal, where the supporting element of the gasket is also able to maintain an efficient seal even at high speeds.

To complete the preliminary analysis, a simulation test was also initiated inside our test room where there is a rotating union test stand. Here the operating conditions present on the customer’s rotary jointwere simulatedand consequently the design approval.

Due to the availability of the semifinished product, we were able to produce the gaskets and deliver them in a short time.

Testimony

We received the gaskets, in hand they looked bigger than the drawing! We immediately mounted them to test them and they turned out perfect. Then off to build “giant” tires.