The thermal-chemical deburring is a process where an explosive mixture of fuel gas and oxygen is fed into a pressure chamber and ignited by a spark. Naturally, such machines underlie increased safety requirements, because they are subject to the “pressure vessel regulations”. All iTEM-systems include the following safety-related single components:
- Sound insulating cabinet This cabinet offers noise protection and, in addition, protection from unintentional reaching.
- Control system The logic part of the control system is a programmable control that is structured as an acknowledging sequence control with repeat lock. This eliminates maloperation of the machine.
- Ignition control unit A minimal-pressure-monitor assures that an ignition can only be initiated, once all necessary closing forces are pending in the cylinders. Due to the combustion of the gas mixture inside the deburring chamber, heat is produced and detected by the ignition control unit. Only after this, the command to open the chamber can be set. When there is no ignition within a determined period of time after the command “ignition on”, viz. no heat is released, the ignition control unit reports “no ignition” and the chamber is bled automatically. ▪ Final pressure of the deburring chamber A maximum permissible chamber filling pressure is preset for every deburring chamber. A maximumpressure- monitor assures that, even in case of maloperation, no overfill of the deburring chamber can occur.
- Opening pressure of the deburring chamber A pressurized deburring chamber can only be opened after a successful ignition or venting of the chamber. The venting is initiated by discharging the deburring chamber via a throttled vent pipe (above roof). Only when the chamber pressure is <1.5 bar (preset pressure switch), the chamber can be opened.
- Gas monitoring system It consists of a central controller and a measuring head. The explosion-proof measuring head is mounted inside the sound insulating cabinet. A congeries of combustible fuel gas inside the sound insulation cabinet leads to the disconnection of the TEM machine’s electrical supply before reaching the lower explosion limit (LEL). The gas supply is also disrupted by the system, as there is an explosion danger in case of spark generation.