Patent ID: 12246433

DESCRIPTION OF THE EMBODIMENTS

As shown inFIG.1, a propellant charge1comprises a central channel11.

Webs2may be located on the wall12of the central channel11of the propellant charge1. The webs2may be formed by propellant overspray or propellant chips that have settled on the wall12of the central channel11.

A device3for removing the webs2comprises an articulated robot arm31which comprises an end31ato which a levelling tool32is attached in order to level the wall12of the central channel11and thus remove the webs2. The levelling of the wall12of the central channel11levels said wall12, thus eliminating the propellant over thicknesses and loosening the propellant chips stuck to the wall12.

As seen inFIG.1, the robot arm31is configured to insert the end31a, and thus the levelling tool32, inside the central channel11. Thus, the robot arm31may comprise a plurality of pivot connections and comprise one or more telescopic portions.

The movements of the robot arm31are controlled by control means33aof a user interface33, thus allowing an operator to control the movements of the robot arm31via the user interface33.

According to a non-limiting example, the control means33aare formed by a joystick, or by a three-dimensional (3D) mouse.

The use of the robot arm31avoids exposing the operator to the pyrotechnical risk of handling the propellant charge1.

Furthermore, as can be seen inFIG.2, a force sensor34is installed on the end31aof the robot arm31in order to measure the force applied by the levelling tool32against the propellant charge1. The force sensor34thus allows the force applied by the levelling tool32against the wall12or against the web2to be measured.

As can be seen inFIG.2, the levelling tool32may be formed by a blade, for example a V-shaped blade. The blade may, for example, be slid beneath the webs2in order to detach said webs2from the wall12of the central channel11.

According to an advantageous variant, the levelling tool32is made of an electrically conductive material, such as metal, and is connected to electrical ground, thus limiting the risk of ignition of the propellant charge1by static electricity.

The device3also comprises a control unit35which regulates the movements of the robot arm31controlled by the control means33aof the user interface33.

The control unit35is connected to the force sensor34and regulates the movements of the levelling tool32by regulating the force applied by the levelling tool32on the propellant charge1.

Furthermore, the control unit35regulates the movements of the robot arm31by regulating the movement speed of the levelling tool32.

The movement speed of the levelling tool32may be calculated by the control unit35from the movements of the various servo motors of the robot arm31. The movement speed of the levelling tool32may also be obtained by an acceleration sensor which is attached to the end31aof the robot arm31, said acceleration sensor being connected to the control unit35.

At least one image sensor36may also be installed on the end31aof the robot arm31so as to acquire images of the surface12of the central channel11and of the levelling tool32.

The user interface33may comprise a display33bthat is connected to said at least one image sensor36, thereby enabling images acquired by said at least one image sensor36to be displayed to the operator.

In association with the at least one image sensor36, the device3may comprise a lighting system that is configured to be attached to the end31aof the robot arm31and that illuminates the interior of the central channel11. According to an advantageous feature, the lighting system comprises several light sources, thereby allowing shadows to disappear or appear on the surface12of the central channel11in order to better appreciate the shape of the web2illuminated by the lighting system. The light sources may, for example, be formed by lamps.

Furthermore, the display33bmay also be used to display the force applied by the levelling tool32, as well as the movement speed of said levelling tool32.

The device3may also comprise a suction nozzle that is configured to be attached to the end31aof the robot arm31, so as to suck up the propellant fragments detached during the removal of the webs2, thus allowing the surface12of the central channel11to be left clean at the end of the removal of the webs2. The device3may comprise a discharge pipe which is connected to a tank in order to discharge the propellant fragments sucked up by the suction nozzle. According to a possible variant, the suction nozzle is integrated with the levelling tool32.

The control unit35is configured to implement a process for removing the webs2formed on the wall12of the central channel11of the propellant charge1.

As shown inFIG.3, the process comprises a step110of removing the webs2by levelling the wall12of the central channel11with the levelling tool32which is installed on the robot arm31. The levelling of the wall12is performed by levelling the wall12by removing the webs2, the levelling of the wall12being carried out with the levelling tool32by detaching the webs2, or by breaking the webs2with the levelling tool32if the webs2are rigid.

In this step110of removing the webs2by levelling the wall12, the movements of the robot arm31are controlled by the user interface33, the user choosing the movements performed by the levelling tool32via the control means33aof the user interface33. The movements of the levelling tool32may comprise moving the levelling tool32along the wall12, pressing the levelling tool32against the webs2, or rotating the levelling tool32to detach or break the webs2.

Furthermore, in this step110of removing the webs2by levelling the wall12, the control unit35regulates the movements of the robot arm31by maintaining the force applied by the levelling tool32below a first predetermined force threshold, the force applied being measured by the force sensor34during step110.

The fact of limiting the force applied by the levelling tool32to below the first force threshold allows for removal of the webs, while limiting the risk of damage to the propellant charge1. The first force threshold may, for example, be comprised between 30 and 100 N. The tangential force to the surface applied to the web2by the levelling tool32may, for example, be comprised between 30 and 100 N.

Furthermore, during the step110of removing the webs2by levelling the wall12, the control unit35also regulates the movements of the robot arm31by maintaining the movement speed of the levelling tool32below a predetermined speed value.

The fact of limiting the movement speed of the levelling tool32below the predetermined speed value during the step110of levelling the wall12limits the risk of igniting the propellant charge1. The speed threshold value may, for example, be comprised between 0.38 cm/sand 0.5 cm/s.

The first force threshold may be variable during the step110of removing the webs2, said first force threshold varying between a minimum value and a maximum value which are predetermined. Thus, the user may increase the force applied by the levelling tool2to yield the web against which the levelling tool2presses, the force not being able to exceed the maximum value in order not to damage the propellant charge1.

The speed threshold value may be variable during the step110of removing the webs2, the speed threshold value varying between a minimum value and a maximum value. Such a variation of the speed threshold value makes it possible, on the one hand, to limit the risks during delicate operations performed by the levelling tool, and on the other hand, to accelerate the levelling tool32when said levelling tool32is not in contact with the propellant charge1.

Furthermore, as shown inFIG.3, the step110of removing the webs2may comprise the following substeps:substep111: placing the levelling tool32against a web2;substep112: pressing the levelling tool32against the web2by progressively increasing the force applied by the levelling tool against the web2and progressively increasing the first force threshold until the web2is detached.

As shown inFIG.3, the process may comprise a step100of probing the wall12which allows the detection of the webs2and which is performed prior to the step110of removing the webs2.

During the probing step100, the levelling tool32is moved along the wall12of the central channel11of the propellant charge1in order to detect the presence of a web2when the levelling tool32abuts against a web2, the movements of the levelling tool32by the robot arm31are controlled by the user interface33.

During the probing step100, the control unit35regulates the movements of the robot arm31by keeping the force applied by the levelling tool32below a second predetermined force threshold which is lower than the first force threshold, the force sensor34measuring the force applied by the levelling tool32during the step100.

The fact of limiting the force applied by the levelling tool32below the second force threshold which is lower than the first force threshold allows the presence and position of a web2to be detected when the levelling tool32abuts against a web2and is unable to advance farther, the force applied by the levelling tool32against the web2being too low to remove said web2. The second force threshold may, for example, be comprised between 0.5 N and 5 N, the second force threshold may for example be equal to 1 N.

Once a web2is detected in step100, step110of removing the web2by levelling is implemented, in particular by increasing the force applied by the levelling tool32.

The probing step100allows a prepositioning of the levelling tool32against the web2before the step110of removing said web2is implemented.

The movement speed of the levelling tool32during the probing step100may be greater than the threshold speed value established for the step110of removing the webs2.

According to a possible variant for limiting the risk of igniting the propellant charge1, during the process for removing the webs2, the control unit35regulates the movements of the robot arm by maintaining the kinetic energy of the robot arm below a predetermined kinetic energy threshold value. To this end, during each movement performed by the robot arm31, the control unit35takes into account the mass of the part of the robot arm31that is set in motion in order to adapt the speed of the part of the robot arm31that is set in motion. Thus, a movement of the robot arm31in which a large part of the robot arm31is set in motion is performed at a low speed, thus limiting the kinetic energy of the robot arm31, whereas a setting in motion of only the levelling tool32can be performed at a higher speed.