DEVICE AND METHOD FOR TERMINATING A SOLID FUEL CHARGE

Description

Technical Field

[0001] The present invention relates to the general field of manufacturing a propellant charge. Previous technique

[0002] Currently, a propellant charge is obtained by pouring a propellant paste into a structure inside which a core has been installed in order to give the desired shape to the propellant charge.

[0003] Once the propellant has solidified, the core is removed.

[0004] A defect that is often encountered during the manufacture of a propellant charge is the appearance of veils, which are excess propellant that have formed due to play between the different elements of the core, and which can be deposited on the inner wall of the central channel of the propellant charge during the removal of the core.

[0005] These propellant veils must be removed from the propellant charge to ensure that the charge possesses the desired characteristics. Currently, this removal step is carried out by operators who manually scrape the inner wall of the propellant charge's central channel with tools to detach the veils.

[0006] However, such a removal step encounters safety problems, notably exposing operators to a pyrotechnic risk.

[0007] US3183592 discloses a manual tool for removing propellant veils from the inner wall of the center channel of a propellant load.

[0008] US5391025 discloses the use in automatic mode of a robotic arm inside a central channel of a propellant load, in order to dig lateral tunnels.

[0009] US2018154518 discloses a robotic arm used in teleoperation mode to perform machining operations on parts. Description of the invention

[0010] The main purpose of the present invention is therefore to provide a solution enabling the safe removal of the foils from a propellant load.

[0011] According to a first aspect, the invention relates to a method for removing film formed on the wall of a central channel of a propellant charge, characterized in that the method comprises a step of removing film by grinding the wall of the central channel of the propellant charge with a grinding tool installed on an articulated robotic arm during which: The movements of the robot arm are controlled by a user interface which includes control means configured for use by a user; a force sensor measures the force applied by the trimming tool; a control unit connected to the force sensor regulates the movements of the robot arm by keeping the force applied by the central trimming tool below a first predetermined force threshold, the control unit also regulating the movements of the robot arm by keeping a trimming tool travel speed below a predetermined speed threshold value.

[0012] Such a process offers the advantage of providing good control of the leveling tool by a user, and helps to limit the risks of damage to the propellant load.

[0013] According to one possible characteristic, the process includes a probing step performed before the veil removal step, during which: The grinding tool is moved along the wall of the central channel of the propellant loading by the robotic arm; the movements of the robotic arm are controlled by the user interface; the force sensor measures the force applied by the grinding tool; the control unit regulates the movements of the robotic arm by keeping the force applied by the grinding tool below a second predetermined force threshold which is lower than the first force threshold.

[0014] Depending on one possible characteristic, the first effort threshold varies between a minimum value and a maximum value that are predetermined.

[0015] Depending on a possible characteristic, the speed threshold value varies between a minimum value and a maximum value which are predetermined.

[0016] Depending on one possible characteristic, the sail removal step includes the following sub-steps: place the trimming tool against a wall; press the trimming tool against the wall while progressively increasing the force applied by the trimming tool against the wall and progressively increasing the first threshold of effort until the wall is detached.

[0017] According to one possible feature, the control unit regulates the movements of the robot arm by keeping the kinetic energy of the robot arm below a predetermined kinetic energy threshold value.

[0018] According to a second aspect, the invention relates to a device for removing film formed on a wall of a central channel of a propellant charge comprising: an articulated robotic arm including an end configured to penetrate inside the central channel of the propellant loading; a trimming tool which is configured to be attached to the end of the robotic arm; a force sensor which is configured to be attached to the end of the robotic arm and which is configured to measure the force applied by the robotic arm; a user interface including control means which are configured to allow control of the movements of the robotic arm by a user;a control unit which is connected to the robot arm and the force sensor, said control unit being configured to regulate the movements of the robot arm by keeping the force applied by the robot arm below a first predetermined force threshold, said control unit being further configured to regulate the movements of the robot arm by keeping the speed of movement of the end of the robot arm below a predetermined speed threshold value.

[0019] According to one possible characteristic, the trimming tool is made of an electrically conductive material and is connected to electrical ground.

[0020] According to one possible feature, the device includes at least one image sensor that is configured to be attached to the end of the robotic arm, and the user interface includes a screen that is configured to display images acquired by said at least one image sensor.

[0021] According to one possible feature, the device includes a lighting system that is configured to be attached to the end of the robot arm.

[0022] According to one possible feature, the device includes a suction nozzle that is configured to be attached to the end of the robot arm. Brief description of the drawings

[0023] Other features and advantages of the present invention will become apparent from the description given below, with reference to the attached drawings which illustrate an example of an embodiment without any limiting character. [ Fig. 1 ] There figure 1 This schematically illustrates a device for removing film formed on the wall of a central channel in a propellant charge. Fig. 2 ] There figure 2 schematically illustrates the end of the robotic arm on which a grinding tool is mounted, located in the central channel of the propellant loading. Fig. 3 ] There figure 3 schematically illustrates the steps of a process for removing the film formed on the wall of a central channel of a propellant charge. Description of the implementation methods

[0024] As illustrated on the figure 1 , a propellant charge 1 includes a central channel 11.

[0025] Sails 2 may be located on the wall 12 of the central channel 11 of the propellant loading 1. The sails 2 may be formed by excess thicknesses of propellant or propellant chips that have been deposited on the wall 12 of the central channel 11.

[0026] A device 3 for removing the sails 2 includes an articulated robotic arm 31 which includes an end 31a on which a grinding tool 32 is fixed in order to grind the wall 12 of the central channel 11 and thus remove the sails 2. Grinding the wall 12 of the central channel 11 makes it possible to level said wall 12, thereby removing the excess thickness of propellant and detaching the propellant chips stuck to the wall 12.

[0027] As seen on the figure 1 , the robot arm 31 is configured to introduce the end 31a, and thus the trimming tool 32, inside the central channel 11. Thus, the robot arm 31 can include a plurality of pivot links and include one or more telescopic portions.

[0028] The movements of the robot arm 31 are controlled by control means 33a of a user interface 33, thus enabling an operator to control the movements of the robot arm 31 via the user interface 33.

[0029] According to a non-limiting example, the control means 33a are formed by a joystick, or by a 3D (3 dimensions) mouse.

[0030] The use of the robotic arm 31 makes it possible to avoid exposing the operator to the pyrotechnic risk due to the handling of the propellant charge 1.

[0031] Furthermore, as can be seen on the figure 2 , a force sensor 34 is installed on the end 31a of the robot arm 31 in order to measure the force applied by the trimming tool 32 against the propellant load 1. The force sensor 34 thus makes it possible to measure the force applied by the trimming tool 32 against the wall 12 or against the web 2.

[0032] As can be seen on the figure 2 The leveling tool 32 can be formed by a blade, for example a V-shaped blade. The blade can, for example, be slid under the walls 2 in order to detach said walls 2 from the wall 12 of the central channel 11.

[0033] According to an advantageous variant, the leveling tool 32 is made of an electrically conductive material, such as metal, and is connected to the electrical ground, thus limiting the risk of ignition of the propellant charge 1 by static electricity.

[0034] Device 3 also includes a control unit 35 which regulates the movements of the robot arm 31 controlled by the control means 33a of the user interface 33.

[0035] The control unit 35 is connected to the force sensor 34, and regulates the movements of the grinding tool 32 by regulating the force applied by the grinding tool 32 on the propellant load 1.

[0036] In addition, the control unit 35 regulates the movements of the robot arm 31 by regulating the speed of movement of the trimming tool 32.

[0037] The travel speed of the trimming tool 32 can be calculated by the control unit 35 from the movements of the various servomotors of the robot arm 31. The travel speed of the trimming tool 32 can also be obtained by an acceleration sensor which is fixed to the end 31a of the robot arm 31, said acceleration sensor being connected to the control unit 35.

[0038] At least one image sensor 36 can also be installed on the end 31a of the robot arm 31 so as to acquire images of the surface 12 of the central channel 11 and of the trimming tool 32.

[0039] The user interface 33 may include a screen 33b which is connected to said at least one image sensor 36, thus enabling the display of images acquired by said at least one image sensor 36 to the operator.

[0040] In conjunction with at least one image sensor 36, the device 3 may include a lighting system configured to be attached to the end 31a of the robotic arm 31 and used to illuminate the interior of the central channel 11. According to an advantageous feature, the lighting system comprises several light sources, thus enabling shadows to be cast or removed on the surface 12 of the central channel 11 in order to better appreciate the shape of the veil 2 illuminated by the lighting system. The light sources may, for example, be lamps.

[0041] In addition, the screen 33b can also be used to display the force applied by the trimming tool 32, as well as the speed of movement of said trimming tool 32.

[0042] Device 3 may also include a suction nozzle configured to be attached to the end 31a of the robotic arm 31, so as to suction up propellant fragments detached during the removal of the sails 2, thus leaving the surface 12 of the central channel 11 clean at the end of the sail removal. Device 3 may include a discharge pipe connected to a reservoir to discharge the propellant fragments suctioned by the suction nozzle. In one possible embodiment, the suction nozzle is integrated into the leveling tool 32.

[0043] The control unit 35 is configured to implement a process for removing the veils 2 formed on the wall 12 of the central channel 11 of the propellant loading 1.

[0044] As illustrated on the figure 3 The process includes a step 110 of removing the walls 2 by leveling the wall 12 of the central channel 11 with the leveling tool 32 which is installed on the robot arm 31. The leveling of the wall 12 is carried out by leveling the wall 12 by removing the walls 2, the leveling of the wall 12 being carried out with the leveling tool 32 by detaching the walls 2, or by breaking the walls 2 with the leveling tool 32 if the walls 2 are rigid.

[0045] In this step 110 of removing the walls 2 by grinding the wall 12, the movements of the robot arm 31 are controlled by the user interface 33, the user choosing the movements performed by the grinding tool 32 via the control means 33a of the user interface 33. The movements of the grinding tool 32 can include in particular the movement of the grinding tool 32 along the wall 12, the pressing of the grinding tool 32 against the walls 2, or a rotation of the grinding tool 32 to detach or break the walls 2.

[0046] Furthermore, in this step 110 of removing the sails 2 by leveling the wall 12, the control unit 35 regulates the movements of the robot arm 31 by keeping the force applied by the leveling tool 32 below a first predetermined force threshold, the applied force being measured by the force sensor 34 during step 110.

[0047] Limiting the force applied by the trimming tool 32 below the first force threshold allows the warps to be removed, while limiting the risk of damage to the propellant charge 1. The first force threshold can, for example, be between 30 and 100 N. The tangential force applied to the surface on the warp 2 by the trimming tool 32 can, for example, be between 30 and 100 N.

[0048] Furthermore, during step 110 of removing the sails 2 by grinding the wall 12, the control unit 35 also regulates the movements of the robot arm 31 by keeping the movement speed of the grinding tool 32 below a predetermined speed value.

[0049] Limiting the speed of the grinding tool 32 below the predetermined speed value during the grinding step 110 of the wall 12 helps to limit the risk of ignition of the propellant charge 1. The threshold speed value can for example be between 0.38 cm / s and 0.5 cm / s.

[0050] The initial force threshold can vary during step 110 of the removal of the 2 shields, this initial force threshold varying between a predetermined minimum and maximum value. Thus, the user can increase the force applied by the trimming tool 2 to break the shield against which the trimming tool 2 is pressing, the force not exceeding the maximum value in order to avoid damaging the propellant charge 1.

[0051] The velocity threshold value can vary during step 110 of the sail removal process, ranging between a minimum and a maximum value. This variation in the velocity threshold value serves two purposes: firstly, to limit risks during delicate operations performed by the trimming tool, and secondly, to accelerate the trimming tool 32 when it is not in contact with the propellant charge 1.

[0052] Furthermore, as illustrated on the figure 3 Step 110 of the removal of the sails 2 may include the following sub-steps: substep 111: place the trimming tool 32 against a wall 2; substep 112: press the trimming tool 32 against the wall 2 by progressively increasing the force applied by the trimming tool against the wall 2 and progressively increasing the first threshold of force until the wall 2 is detached.

[0053] As illustrated on the figure 3 The process may include a step 100 of probing the wall 12 which allows the detection of the veils 2 and which is carried out before step 110 of removing the veils 2.

[0054] During the probing step 100, the grinding tool 32 is moved along the wall 12 of the central channel 11 of the propellant loading 1 in order to detect the presence of a wall 2 when the grinding tool 32 hits a wall 2, the movements of the grinding tool 32 by the robotic arm 31 are controlled by the user interface 33.

[0055] During probing step 100, the control unit 35 regulates the movements of the robot arm 31 by keeping the force applied by the trimming tool 32 below a second predetermined force threshold which is lower than the first force threshold, the force sensor 34 measuring the force applied by the trimming tool 32 during step 100.

[0056] Limiting the force applied by the trimming tool 32 below the second force threshold, which is lower than the first force threshold, allows the presence and position of a wall 2 to be detected when the trimming tool 32 hits a wall 2 and can no longer advance, the force applied by the trimming tool 32 against the wall 2 being too weak to remove said wall 2. The second force threshold can, for example, be between 0.5N and 5N, the second force threshold being, for example, equal to 1N.

[0057] Once a veil 2 is detected during step 100, step 110 of removing the veil 2 by grinding is implemented, in particular by increasing the force applied by the grinding tool 32.

[0058] The probing step 100 allows pre-positioning of the trimming tool 32 against the wall 2 before the implementation of step 110 of removal of said wall 2.

[0059] The speed of movement of the trimming tool 32 during the probing step 100 may be greater than the threshold speed value established for the removal of the sails 2 step 110.

[0060] According to a possible variant that limits the risk of ignition of the propellant charge 1 during the sail removal process 2, the control unit 35 regulates the movements of the robotic arm by maintaining its kinetic energy below a predetermined threshold value. To achieve this, during each movement of the robotic arm 31, the control unit 35 takes into account the mass of the moving portion of the robotic arm 31 in order to adjust the speed of that portion. Thus, a movement of the robotic arm 31 in which a significant portion of the arm is in motion is performed at a low speed, thereby limiting the kinetic energy of the robotic arm 31, while a movement of only the trimming tool 32 can be performed at a higher speed.

Claims

1. A process for removing webs (2) formed on a wall (12) of a central channel (11) of a propellant charge (1), characterized in that the process comprises a step (110) of removing webs (2) by levelling the wall (12) of the central channel (11) of the propellant charge (1) with a levelling tool (32) installed on an articulated robot arm (31) during which: - the movements of the robot arm (31) are controlled by a user interface (33) which comprises control means (33a) configured to be used by a user; - a force sensor (34) measures the force applied by the levelling tool (32); - a control unit (35) connected to the force sensor (34) regulates the movements of the robot arm (31) by maintaining the force applied by the levelling tool (32) below a first predetermined force threshold, the control unit (35) also regulating the movements of the robot arm (31) by maintaining a movement speed of the levelling tool (32) which is below a predetermined speed threshold value.

2. The process as claimed in claim 1, wherein the process comprises a probing step (100) performed before the step (110) of removing the webs (2) and during which: - the levelling tool (32) is moved along the wall (12) of the central channel (11) of the propellant charge (1) by the robot arm (31); - the movements of the robot arm (31) are controlled by the user interface (33); - the force sensor (34) measures the force applied by the levelling tool (32); - the control unit (35) regulates the movements of the robot arm (31) by maintaining the force applied by the levelling tool (32) below a second predetermined force threshold which is lower than the first force threshold.

3. The process as claimed in any one of claims 1 to 2, wherein the first force threshold varies between a minimum value and a maximum value which are predetermined.

4. The process as claimed in any one of claims 1 to 3, wherein the speed threshold value varies between a minimum value and a maximum value which are predetermined.

5. The process as claimed in claim 3, wherein the step (110) of removing webs (2) comprises the following substeps: - (111): placing the levelling tool (32) against a web (2); - (112): pressing the levelling tool (32) against the web (2) by progressively increasing the force applied by the levelling tool (32) against the web (2) and by progressively increasing the first force threshold until the web (2) is detached.

6. The process as claimed in any one of claims 1 to 5, wherein the control unit (35) regulates the movements of the robot arm (31) by keeping the kinetic energy of the robot arm (31) below a predetermined kinetic energy threshold value.

7. A device (3) for removing webs (2) formed on a wall (12) of a central channel (11) of a propellant charge (1) comprising: - an articulated robot arm (31) comprising an end (31a) configured to penetrate into the central channel (11) of the propellant charge (1); - a levelling tool (32) which is configured to be attached to the end (31a) of the robot arm (31) - a force sensor (34) which is configured to be attached to the end of the robot arm (31) and which is configured to measure the force applied by the robot arm (31) - a user interface (33) comprising control means (33a) which are configured to allow control of the movements of the robot arm (31) by a user; - a control unit (35) which is connected to the robot arm (31) and to the force sensor (34), said control unit (35) being configured to regulate the movements of the robot arm (31) by maintaining the force applied by the robot arm (31) below a first predetermined force threshold, said control unit (35) being further configured to regulate the movements of the robot arm (31) by maintaining a movement speed of the end (31a) of the robot arm (31) which is below a predetermined speed threshold value.

8. The device (3) as claimed in claim 7, wherein the levelling tool (32) is made of an electrically conductive material and is connected to electrical ground.

9. The device (3) as claimed in any one of claims 7 or 8, wherein the device (3) comprises at least one image sensor which is configured to be attached to the end (31a) of the robot arm (31), and the user interface (33) comprises a display (33b) which is configured to display images acquired by said least one image sensor.

10. The device (3) as claimed in claim 9, wherein the device (3) comprises a lighting system which is configured to be attached to the end (31a) of the robot arm (31).

11. The device (3) as claimed in any one of claims 7 to 10, wherein the device (3) comprises a suction nozzle which is configured to be attached to the end (31a) of the robot arm (31).