AUTOMATIC CONTROL SYSTEM FOR A CONCRETE DISTRIBUTING PIPE IN TUNNEL LINING

Abstract: System for performing automatic movement of the end pipe of the arm supplying fluid concrete mixes and air (shotcrete) in machines for lining tunnel vaults and the like, in which electrohydraulic actuators for the movements of the pipe are controlled by sending to them electrical commands in the form of square-wave signals with a variable frequency and in appropriate sequences, a signal being provided for each type of desired movement.

Description: AUTOMATIC CONTROL SYSTEM FOR A CONCRETE DISTRIBUTING PIPE IN TUNNEL LINING The present invention relates to a system for automatically moving the end pipe of the arm supplying fluid concrete mixes and air in machines for lining tunnel vaults and the like, intended to improve the working conditions in tunnels, freeing the operators of the need to perform continuous repetitive manual operations for said movement, thus leaving them free to concentrate on other, more demanding operations. Machines with articulated arms for spraying fluid concrete mixes and air (shotcrete) onto the vaults of tunnel excavations (using the so-called "spritz beton" method), in order to stabilise or directly line the tunnel, are known and widely used in the building sector. In these machines the articulated arm is provided, at its operating end, with a spraying pipe which is able to perform cyclical controlled oscillating movements both in the vertical plane (vertical traversing) and in the horizontal plane (horizontal traversing) from a starting position, whereby both the starting position and amplitude of the traversing movements of the pipe may be modified. At present, control of the pipe movements is carried out by the operator who performs said control manually by means of electrohydraulic actuators. This control is continuous and repetitive and therefore demanding and tiring; moreover, it is not easy to perform in a precise manner and, when it is not performed properly (as inevitably tends to happen at least occasionally) it may give rise to an undesirable lack of uniformity in the lining obtained; therefore, the advantage which would be gained by automating said operation is apparent. The object of the present invention is precisely to provide this automatic system, thus facilitating the task of the operator and improving the reliability and the work quality. For this purpose the present invention envisages controlling the electrohydraulic actuators for the pipe movements by sending to them electrical commands in the form of square-wave signals with a variable frequency and in appropriate sequences, one signal being provided for each type of desired movement. Preferably, at least three signals are provided: the first signal which controls the vertical traversing movements, the second signal which controls the horizontal traversing movements, and the third signal which controls both the said movements in a predetermined combination. Also preferably, the signals used are simple square-wave signals which are sent to the solenoids of solenoid valves of said electrohydraulic actuators. So as not to shift unintentionally the starting position of the pipe during its movements, it is envisaged that the first wave of said signals should have a period equal to half the period of the subsequent waves. In order to vary the amplitude of the pipe movements, the frequency of the said signals is varied. The system is provided using a PLC which generates the necessary sequences of output signals, allowing the frequency and the sequence thereof to be varied on the basis of incoming commands effected by the operator via a remote control device. The invention is now described in greater detail with reference to the accompanying drawings in which: Fig. 1 shows a diagram of the movement system according to the invention; Fig. 2 shows the sequence of signals for obtaining vertical traversing or horizontal traversing of the pipe separately; and Fig. 3 shows the sequence of signals for obtaining a combined traversing movement of the said pipe. As it is known, the movement of the end pipe of the arm for supplying fluid concrete mixes and air (shotcrete) in machines for lining tunnel vaults and the like is obtained in a known manner by means of electrohydraulic actuators. More precisely, with reference to Fig. 1 of the drawings, these actuators comprise, in the system according to the invention, a cylinder-and-piston unit 1 controlled by a solenoid valve 2 for performing the vertical traversing movements of the pipe, while the horizontal traversing movements of the pipe itself are obtained by means of a rotary actuator 3, controlled by a solenoid valve 4. According to the invention, the solenoid valves 2 and 4 - in addition to being able to be operated manually, as in the known art - are controlled in an automated manner. For this purpose, a PLC 5, which is controlled by the operator by means of a remote control device 6, sends, by means of outputs 7, 8, 9 and 1 0, square-wave signals to the said solenoid valves 2 and 4. In order to obtain vertical traversing, pairs of square-wave signals, such as those shown in Fig. 2, are sent to the two solenoids of the solenoid valves 2 from the outputs 7 and 9; in order to obtain horizontal traversing, pairs of square-wave signals, such as those shown in Fig. 2, are also sent to the two solenoids of the solenoid valve 4, from the outputs 8 and 1 0; on the other hand, a more complex combined movement of vertical and horizontal traversing is obtained by sending to the solenoid valves 2 and 4 the two pairs of signals according to Fig. 3 from four outputs 7 to 1 0, the pipe in this case describing substantially a square shape. All these signals have a period T which may be varied by the operator via the remote control device 6, the first pulse of which must have a period T/2, if it is required to avoid displacement of the starting position of the pipe movements. It is understood that some of the choices made in the embodiment illustrated may be different, without departing from the protective scope of the invention: for example, instead of square-wave signals, other types of signals could be used, depending on the type of hydraulic system adopted. In this case, obviously different movements would be obtained.

Claims: CLAIMS 1 . System for performing automatic movement of the end pipe of the arm supplying fluid concrete mixes and air (shotcrete) in machines for lining tunnel vaults and the like, characterised in that electrohydraulic actuators for the movements of the pipe are controlled by sending to them electrical commands in the form of square-wave signals with a variable frequency and in appropriate sequences, a signal being provided for each type of desired movement. 2. System as claimed in Claim 1 , wherein at least three signals are provided: the first signal which controls the vertical traversing movements of the pipe, the second signal which controls its horizontal traversing movements, and the third signal which controls both the said movements of the pipe in a predetermined combination. 3. System as claimed in Claims 1 and 2, wherein the signals used are simple square-wave signals which are sent to the solenoids of solenoid valves of said electrohydraulic actuators. 4. System as claimed in Claims 1 to 3, wherein, so as not to shift unintentionally the starting position of the pipe during its movements, the first wave of said signals has a period equal to half the period of the subsequent waves. 5. System as claimed in Claims 1 to 4, wherein the frequency of the said signals is varied in order to vary the amplitude of the pipe movements. 6. System as claimed in Claims 1 to 5, carried out using a PLC which generates the necessary sequences of square-wave signals output therefrom, allowing the frequency and the sequence thereof to be varied on the basis of incoming commands effected by the operator via a remote control device.

Inventors: ARPINI ROBERTO, MORETTI GIORGIO, ARPINI, ROBERTO, MORETTI, GIORGIO
Applicants: ARPINI ROBERTO, CIFA SPA, MORETTI GIORGIO, ARPINI, ROBERTO, CIFA S.P.A., MORETTI, GIORGIO
Application year: 1998
Main classification: E21D11
IPC codes: E21D11, F15B11, G05B11