Method for measuring the volume of a propellant chamber and device therefor

Abstract

This invention proposes a projectile chamber volume measuring device and discloses a method and apparatus for measuring projectile chamber volume, relating to the field of projectile chamber volume measurement. The device includes a measuring frame with a rotating spindle, a slide rail, and a computer. The rotating spindle drives the projectile under test to rotate via a three-jaw chuck. A slider on the slide rail is equipped with a grating displacement sensor to monitor the slider's position. The slider can reciprocate along the length of the slide rail. A support rod is mounted on the slider, and a point laser displacement sensor and a miniature stepper motor are mounted on the support rod to collect the projectile chamber diameter information. The computer receives data from the spindle encoder, grating displacement sensor, and point laser displacement sensor, processes the data, and calculates the volume value. The method and apparatus of this invention enable rapid, non-contact measurement of the projectile chamber, overcoming the shortcomings of the traditional "water weighing method" which requires subsequent drying of the projectile and rust prevention.

Description

Technical Field

[0001] This invention relates to a method and apparatus for measuring the volume of an internal cavity. Background Technology

[0002] The projectile chamber is a crucial component affecting projectile performance. Its volume determines the density of the explosive charge, which in turn determines the mass of the explosive charge, thus controlling the explosive density. Excessive explosive density may lead to barrel explosion, while insufficient density will negatively impact the projectile's destructive performance. Therefore, high-precision measurement of the projectile chamber's geometric parameters is of paramount importance.

[0003] The traditional measurement method currently used is mainly the "water weighing method," which calculates the volume of the projectile's propellant chamber by dividing the mass difference before and after water injection by the density of water. However, this method is inefficient due to its reliance on manual calculations. Furthermore, it is a contact-based measurement method, requiring the chamber to be dried after each measurement, a cumbersome process that also contaminates the chamber and adds difficulty to subsequent rust prevention.

[0004] Currently, a method for measuring the volume of artillery propellant chambers using laser triangulation has been proposed. This method involves placing a laser displacement sensor into the propellant chamber using a centering mechanism. A rotary stepper motor and a propulsion stepper motor drive the mechanism to perform circular measurements of the target chamber's cross-section. Each measured cross-section is followed by a forward stepper motor movement, and the diameter is obtained by calculating the maximum chord length of each cross-section. This method is suitable for large-diameter straight-through pipes. To ensure high accuracy, the stepping distance needs to be sufficiently small, which leads to long data acquisition times and low detection efficiency. Furthermore, the addition of a centering mechanism may damage the inner wall of the propellant chamber, causing changes in volume.

[0005] Therefore, in order to solve the above problems, it is necessary to design a new non-contact method for measuring the volume of projectile propellant chambers to improve the efficiency of projectile propellant chamber volume detection. Summary of the Invention:

[0006] To address the aforementioned problems in the prior art, this invention provides a novel method and apparatus for measuring the volume of a projectile chamber, which can improve upon the above deficiencies.

[0007] The technical solution of the present invention: The present invention provides a method for measuring the volume of a projectile's propellant chamber, characterized by comprising the following steps:

[0008] (1) Place the projectile to be tested on the three-jaw chuck and clamp it. Adjust the initial position of the slider so that the point laser displacement sensor is located at the opening of the projectile to be tested.

[0009] (2) The starting device makes the rotating spindle rotate at a certain speed, and the slider slides down along the length of the slide rail at a certain speed;

[0010] (3) Make the rotary spindle encoder, grating displacement sensor, and point laser displacement sensor sample at the same sampling frequency, wherein the data α collected by the spindle encoder i For the angle information of the i-th sampling point, the data z collected by the grating displacement sensor i The Z-axis coordinate information of the i-th sampling point is the data r collected by the point laser displacement sensor. j The distance from the i-th sampling point to the laser emission point of the laser displacement sensor;

[0011] (4) The sampling data from the rotary spindle encoder, grating displacement sensor, and point laser displacement sensor are transmitted to the computer. The computer processes and calculates the received data. The spatial coordinates of the i-th sampling point on the inner wall of the projectile chamber are (x... i ,y i ,z i ),in z i =z i (in Let P be the angle between the laser direction of the point laser displacement sensor and the direction perpendicular to the projectile axis, thus obtaining the point cloud P = {p1, p2, ..., p} of the inner wall of the projectile's propellant chamber. n},p i =(x i ,y i ,z i )∈R 3 ;

[0012] (5) Filter the point cloud information of the inner wall of the projectile chamber and calculate the density of the processed point cloud. Where ρ is the point cloud density, V t For all raster numbers, V c Let K be the total number of empty grid cells, K be the number of neighboring points, and n be the total number of point clouds.

[0013] (6) Slice the processed point cloud into n point cloud slices of equal thickness δ, where δ = β × ρ, β is an empirical coefficient (generally taken as 0.4-0.8), and ρ is the point cloud density. Project each point cloud slice onto the XOY plane, and fit the projected contour into a two-dimensional circle to obtain the radius R of each circle. j Set a threshold R. t Determine if the difference in radius between adjacent slices is |R i+1 -R i |≤R t If so, merge the two slices. The thickness of the merged slice is 2δ. Repeat the above steps until there are no more slices to merge.

[0014] (7) Calculate the area S of each slice using the formula for the area of ​​a circle.j Ultimately, through the formula Calculate the volume V of the drug chamber, where n is the number of slices after step (6), and δ i To determine the thickness of each slice after step (6), S j The area of ​​the slice after step (6) is denoted as .

[0015] A projectile chamber volume measuring device includes a measuring frame, on which a rotating spindle, a slide rail, and a computer are mounted. The projectile to be measured is connected to the spindle by being clamped by a three-jaw chuck, and the spindle drives it to rotate. A slider is mounted on the slide rail and can reciprocate along the length of the slide rail. A grating displacement sensor is mounted on one side of the slider, and a grating ruler is mounted on the slide rail on the same side.

[0016] This solution also relates to a measuring device for the volume of a projectile chamber, including a measuring frame, on which a rotating spindle, a slide rail, and a computer are mounted. The projectile to be tested is mounted on the rotating spindle of the measuring frame. An encoder is mounted on the rotating spindle. A three-grip chuck is mounted on the rotating spindle. A slider is mounted on the slide rail and can reciprocate along the length of the slide rail. A grating displacement sensor is mounted on one side of the slider, and a grating ruler is mounted on the same side of the slide rail. The encoder, grating displacement sensor, and point laser displacement sensor on the rotating spindle are connected to the computer via signals.

[0017] Furthermore, a support rod is installed on the slider, and a micro stepper motor is installed at the front end of the support rod. The spindle of the micro stepper motor is connected to the base of the point laser displacement sensor, which can control its rotation.

[0018] Furthermore, the encoder on the rotating spindle transmits the angular displacement and coordinate information of the projectile to be tested to the computer.

[0019] Furthermore, the slider slides downwards along the axis of the projectile, and the grating displacement sensor on the slider transmits the displacement coordinates of the slider, i.e., the coordinate information of the point laser displacement sensor, to the computer.

[0020] Furthermore, the point laser displacement sensor transmits the inner diameter information of the projectile's internal propellant chamber wall to the computer.

[0021] The measuring device of the present invention has the following characteristics compared with the prior art:

[0022] 1. Non-contact measurement: This device obtains the inner diameter information of the projectile's propellant chamber through a point laser displacement sensor and combines it with the coordinate information of the grating ruler and the rotary spindle encoder to obtain the inner wall information of the projectile's propellant chamber. The volume of the propellant chamber can then be calculated.

[0023] 2. High measurement efficiency: While the device rotates the projectile under test, the support rod with a point laser displacement sensor is simultaneously extended into the projectile's chamber along the projectile's axis on the slider. The point cloud information of the inner wall of the projectile's chamber is collected in a spiral manner. The adaptive slice thickness method is used to further reduce the computational complexity and improve the detection efficiency. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the invention.

[0025] Figure 2 This is a side view of the present invention.

[0026] Figure 3 This is a magnified view of a portion of point A.

[0027] Figure 4 A schematic diagram of the mounting structure for a laser sensor base.

[0028] The diagram shows: 1. Measuring frame, 2. Rotary spindle, 3. Three-jaw chuck, 4. Test projectile, 5. Computer, 6. Miniature progress motor, 7. Point laser displacement sensor, 8. Slide rail, 9. Grating displacement sensor, 10. Support rod, 11. Slider, 12. Laser sensor base. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0030] In practice, a method for measuring the volume of a projectile chamber includes the following steps:

[0031] (1) Place the projectile to be tested on the three-jaw chuck and clamp it. Adjust the initial position of the slider so that the point laser displacement sensor is located at the opening of the projectile to be tested.

[0032] (2) The starting device makes the rotating spindle rotate at a certain speed, and the slider slides down along the length of the slide rail at a certain speed;

[0033] (3) Make the rotary spindle encoder, grating displacement sensor, and point laser displacement sensor sample at the same sampling frequency, wherein the data α collected by the spindle encoder i For the angle information of the i-th sampling point, the data z collected by the grating displacement sensor i The Z-axis coordinate information of the i-th sampling point is the data r collected by the point laser displacement sensor. j The distance from the i-th sampling point to the laser emission point of the laser displacement sensor;

[0034] (4) The sampling data from the rotary spindle encoder, grating displacement sensor, and point laser displacement sensor are transmitted to the computer. The computer processes and calculates the received data. The spatial coordinates of the i-th sampling point on the inner wall of the projectile chamber are (x... i ,y i ,z i ),in z i =z i (in Let P be the angle between the laser direction of the point laser displacement sensor and the direction perpendicular to the projectile axis, thus obtaining the point cloud P = {p1, p2, ..., p} of the inner wall of the projectile's propellant chamber. n},p i =(x i ,y i ,z i )∈R 3 ;

[0035] (5) Filter the point cloud information of the inner wall of the projectile chamber and calculate the density of the processed point cloud. Where ρ is the point cloud density, V t For all raster numbers, V c Let K be the total number of empty grid cells, K be the number of neighboring points, and n be the total number of point clouds.

[0036] (6) Slice the processed point cloud into n point cloud slices of equal thickness δ, where δ = β × ρ, β is an empirical coefficient (generally taken as 0.4-0.8), and ρ is the point cloud density. Project each point cloud slice onto the XOY plane, and fit the projected contour into a two-dimensional circle to obtain the radius R of each circle. j Set a threshold R. t Determine if the difference in radius between adjacent slices is |R i+1 -R i |≤R t If so, merge the two slices. The thickness of the merged slice is 2δ. Repeat the above steps until there are no more slices to merge.

[0037] (7) Calculate the area S of each slice using the formula for the area of ​​a circle. j Ultimately, through the formula Calculate the volume V of the drug chamber, where n is the number of slices after step (6), and δ i To determine the thickness of each slice after step (6), S j The area of ​​the slice after step (6) is denoted as .

[0038] This solution also proposes a measuring device, such as... Figure 1-4As shown, a projectile chamber volume measuring device includes a measuring frame 1. A rotating spindle 2, a slide rail 8, and a computer 5 are mounted on the measuring frame 1. A three-jaw chuck 3 is mounted on the rotating spindle 2 to hold the projectile 4 to be tested. The rotating spindle 2 drives the projectile 4 to rotate. An encoder on the rotating spindle 2 transmits the angular displacement and coordinates of the projectile 4 to the computer 5. A slider 11 is mounted on the slide rail 8, and a support rod 10 is mounted on the slider 11. A grating displacement sensor 9 is mounted on one side of the slider 11, and a grating ruler is mounted on the same side of the slide rail 8. The grating displacement sensor 9 collects the slider displacement and coordinate information and transmits it to the computer 5. A micro stepper motor 6 is mounted at the front end of the support rod 10. A point laser displacement sensor 7 is mounted on the shaft of the micro stepper motor 6 via a laser sensor base 12. The point laser displacement sensor transmits the inner diameter information of the projectile chamber to the computer 5.

[0039] When using this device to measure the volume of a projectile's propellant chamber, firstly, the projectile to be tested is placed on a three-jaw chuck and clamped. The slider position is adjusted so that the point laser displacement sensor is at the opening of the projectile's propellant chamber. After starting the system, the rotating spindle begins to rotate the projectile at a certain speed, while the slider begins to slide downwards. The support rod extends the point laser displacement sensor into the propellant chamber along the projectile's axis. During this process, the encoder, grating displacement sensor, and point laser displacement sensor of the rotating spindle sample at the same sampling frequency, and the sampled data is transmitted to the computer. The data α collected by the spindle encoder is... i For the angle information of the i-th sampling point, the data z collected by the grating displacement sensor i The Z-axis coordinate information of the i-th sampling point is the data r collected by the point laser displacement sensor. j Let be the distance from the i-th sampling point to the laser emission point of the point laser displacement sensor. The sampling data from the rotary spindle encoder, grating displacement sensor, and point laser displacement sensor are transmitted to the computer. The computer processes and calculates the received data. The spatial coordinates of the i-th sampling point on the inner wall of the projectile chamber are (x...). i ,y i ,z i ),in z i =z i (in Let P be the angle between the laser direction of the point laser displacement sensor and the direction perpendicular to the projectile axis, thus obtaining the point cloud P = {p1, p2, ..., p} of the inner wall of the projectile's propellant chamber. n},p i =(x i ,y i ,z i )∈R 3The point cloud information of the inner wall of the projectile propellant chamber is filtered, and the processed point cloud is sliced ​​into n point cloud slices of equal thickness δ. Each point cloud slice is projected onto the XOY plane, and the projected contour is fitted into a two-dimensional circle to obtain the radius R of each circle. j The area S of each slice is calculated using the formula for the area of ​​a circle. j Ultimately, through the formula Find the volume V of the medicine chamber.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for measuring the volume of a projectile's propellant chamber, characterized in that: Includes the following steps: (1) Place the projectile to be tested on the three-jaw chuck and clamp it. Adjust the initial position of the slider so that the point laser displacement sensor is located at the opening of the projectile to be tested. (2) The starting device makes the rotating spindle rotate at a certain speed, and the slider slides down along the length of the slide rail at a certain speed; (3) Make the rotary spindle encoder, grating displacement sensor, and point laser displacement sensor sample at the same sampling frequency, wherein the data α collected by the spindle encoder i For the angle information of the i-th sampling point, the data z collected by the grating displacement sensor i The Z-axis coordinate information of the i-th sampling point is the data r collected by the point laser displacement sensor. j The distance from the i-th sampling point to the laser emission point of the laser displacement sensor; (4) The sampling data from the rotary spindle encoder, grating displacement sensor, and point laser displacement sensor are transmitted to the computer. The computer processes and calculates the received data. The spatial coordinates of the i-th sampling point on the inner wall of the projectile chamber are (x... i ,y i ,z i ),in z i =z i (in Let P be the angle between the laser direction of the point laser displacement sensor and the direction perpendicular to the projectile axis, thus obtaining the point cloud P = {p1, p2, ..., p} of the inner wall of the projectile's propellant chamber. n },p i =(x i ,y i ,z i )∈R 3 ; (5) Filter the point cloud information of the inner wall of the projectile chamber and calculate the density of the processed point cloud. Where ρ is the point cloud density, V t For all raster numbers, V c Let K be the total number of empty grid cells, K be the number of neighboring points, and n be the total number of point clouds. (6) Slice the processed point cloud into n point cloud slices of equal thickness δ, where δ = β × ρ, β is an empirical coefficient (generally taken as 0.4-0.8), and ρ is the point cloud density. Project each point cloud slice onto the XOY plane, and fit the projected contour into a two-dimensional circle to obtain the radius R of each circle. j Set a threshold R. t Determine if the difference in radius between adjacent slices is |R i+1 -R i |≤R t If so, merge the two slices. The thickness of the merged slice is 2δ. Repeat the above steps until there are no more slices to merge. (7) Calculate the area S of each slice using the formula for the area of ​​a circle. j Ultimately, through the formula Calculate the volume V of the drug chamber, where n is the number of slices after step (6), and δ i To determine the thickness of each slice after step (6), S j The area of ​​the slice after step (6) is the area of ​​the slice.

2. A projectile chamber volume measuring device, characterized in that: The system includes a measuring frame, on which a rotating spindle, a slide rail, and a computer are mounted. The projectile to be tested is mounted on the rotating spindle of the measuring frame. An encoder is mounted on the rotating spindle. A three-grip chuck is mounted on the rotating spindle. A slider is mounted on the slide rail and can reciprocate along the length of the slide rail. A grating displacement sensor is mounted on one side of the slider, and a grating ruler is mounted on the same side of the slide rail. The rotating spindle encoder, grating displacement sensor, and point laser displacement sensor are connected to the computer via signals.

3. The projectile chamber volume measuring device according to claim 2, characterized in that: A support rod is installed on the slider.

4. The projectile chamber volume measuring device according to claim 3, characterized in that: A miniature progress motor is fixed to the front end of the support rod by bolts.

5. The projectile chamber volume measuring device according to claim 4, characterized in that: A point laser displacement sensor is fixed on the shaft of the micro-progress motor via a laser sensor base.

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