Looking at peening and blasting equipment, shot flow is probably the most critical parameter to ensure that a process can be carried out according to specifications or requirements. Especially looking at peening applications, too little or too much media flow can result in the wrong intensity and coverage, which is an unacceptable situation. For that reason, many specifications determine within what parameters the flow rate has to be controlled.

Peening Accessories GmbH, which is on one the hand a manufacturer of Almen gages, holders and strips, and on the other hand a distributor of various auxiliary products for the shot peening industry, decided to develop its own valve for shot flow control. The whole project was a time consuming undertaking. All major specifications for the aerospace and automotive industries had to be fulfilled. Furthermore the valve was to be installed on new machines and had to be used as an easy retrofit kit for exiting equipment.
 
Electromagnetic Principle

Listening to the feedback of the industry concerning such valves for many years, two aspects seem to have been of greatest concern. Firstly, a given and specified accuracy in terms of flow rate shall be steady over years of use, which means that the accuracy should not change over time. Secondly, knowing that some machines may need 8 or more such valves, the device should be cost effective, without jeopardizing quality. After investigating various concepts, it was found that by integrating an electromagnetic principle to control the shot flow, all the requirements could be fulfilled. The main advantage of an electromagnetic magnet is that unlike a permanent magnet, it does not change its performance characteristics. So it will not have to be readjusted and re-calibrated so often. In addition, electromagnets are much less expensive than high-quality permanent magnets.

General Information

Like any magnetically driven flow control system, the E-valve has no moving parts and therefore causes very little wear. The required height to install such a valve is only 250 mm and the light weight of the valves makes easy handling possible. The device can be used for either wheel or air driven types of peening and blasting machines.  It will display the media flow rate in kg/min or lbs/min with the required repeatability. Repeatability is a key issue for such a valve, since without this necessity no uniform process can be guaranteed. A certain nominal set up of the flow rate must correspond to the actual flow rate. A sensor at the valve is, using a closed loop system, connected to the controllers and makes sure of that. All data can be recorded and on request, be integrated into a process visualization program. The valve can also be easily opened and closed via an ON/OFF function. Any kind of magnetic media such as steel grit, cast steel shot or cut wire shot will work with this new system. The valves have the necessary interfaces to be connected to any standard PLC control. Depending on requirement, a small PLC controller can be purchased with the valve. The new valve will be able to set new standards for flow rate control within the industry.

Official Market Introduction

Presently final tests are carried out in-house and with chosen test partners. The first E-valve model will be for wheel machines and covers a flow range of 50-300 kg/min. The official market introduction is planned for March 2010.

For Information:
Peening Accessories GmbH
Tel. +41.44.8312644, Switzerland
E-mail: info@peening.ch
www.peening.ch