Design and analysis of modular charge feeding mechanism

LIU Hai-gang, WANG Gang, XIONG Sheng, LIU Peng-fei, ZHANG Xiao-zhong

(College of Mechatronic Engineering, North University of China, Taiyuan 030051, China)

劉海剛， 王 剛， 熊 勝， 劉鵬飛， 張孝忠

(中北大學 機電工程學院， 山西 太原 030051)

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Design and analysis of modular charge feeding mechanism

LIU Hai-gang, WANG Gang, XIONG Sheng, LIU Peng-fei, ZHANG Xiao-zhong

(CollegeofMechatronicEngineering,NorthUniversityofChina,Taiyuan030051,China)

Aiming at the turning motion’s disadvantages, including the instability of charge magazine caused by polygon effect and the disability of synchronously pushing modular charge of the current pushing mechanism, a new type of charge feeding mechanism is designed. It can not only select modular charge rapidly and steadily, but also push a certain amount of modular charge into the tray which is used to receive the charge synchronously. The selection and push principles of feeding mechanism are introduced, and a three-dimensional model is established. ADAMS is applied to simulation analysis of the feeding mechanism. The results show that the feeding mechanism can push the modular charge into the reception tray rapidly and steadily, which provides a theoretical basis for the practical design.

modular charge; polygon effect; feeding mechanism; ADAMS； reception tray

The traditional large-caliber artillery charge feeding system usually uses chain slewing mechanism with coarse pitch, fewer sprocket teeth and slow speed revolution[1-4]. Due to obvious polygon effect of chain transmission, the slewing motion of the cartridge becomes unstable. Because of the simplification of its function, the traditional charge feeding mechanism can not easily push a certain amount of modular charge from the magazine into the reception tray synchronously[5]. Therefore, a new type of modular charge feeding mechanism adopting gear drive and spiral drive is designed. It overcomes the shortcomings caused by the polygon effect of chain transmission and makes the motion of the magazine stable. According to the demand of shooting, the designed modular charge feeding mechanism can push the desired modular charge into the charge reception tray.

1 Structure of charge feeding mechanism

The structure of modular charge feeding mechanism is shown in Fig.1.

Fig.1 Structure of modular charge feeding mechanism

It is composed of modular charge magazine by gear drive and modular charge pushing mechanism. The pushing mechanism lies inside the modular charge magazine. When the magazine turns a certain angle counterclockwise, it will pause temporarily. Then the pushing mechanism pushes the desired modular charge verically into the reception tray. Thus the motion of modular charge feeding is completed.

1.1 Working principle and composition of modular charge magazine

The composition of modular charge magazine is shown in Fig.2. It consists of a electric motor, a reducer, a star-wheel, a restraint track, a ring rack, twelve modular charge storage devices and a gear set. Twelve modular charge storage devices are located in the ring rack homogeneously. The modular charge storage device is a semicircular cylinder with some steel boards inside. It is used to place eight modular charges, two of which are storage charges. The modular charge clipping boards are installed in the semicircular cylinder. They are used to clamp the modular charges when the modular charge storage device turns over to avoid the modular charge getting out of the magazine when overloaded. There are rolling gears on two sides of the semicircular cylinder, which can circle around the ring rack. The transmission gear is between every two rolling gears of modular charge storage device. It is mainly used to make the two rolling gears roll synchronously. Therefore, twelve rolling gears can roll synchronously.

Fig.2 Composition of modular charge magazine

The rotation of modular charge storage device mainly depends on the rolling gear in the ring rack, and the rolling of gear depends on the star-wheel. The star-wheel is similar to the chain wheel in the chain transmission, and it is used to push the short axle of the modular charge storage device. The short axle can only move along the circular orbit under the influence of restraint track. When the star-wheel pushes the short axle, it is similar to the planet frame, which composes the cycle system with the rolling gear, ring rack and restraint track. Therefore, the rolling gear can circle around the ring rack. With the impact of the gear drive, other gears will roll successively, then the rotation of modular charge storage device can be achieved.

The structure of modular charge clipping mechanism is shown in Fig.3.

The clipping mechanism can clip, locate and release. Due to the rotation of modular charge storage device, the modular charge will depart from the storage mechanism so easily that it will influence the pushing motion. Therefore, it is very important whether the design of clipping mechanism is reasonable or not.

The clipping mechanism is mainly composed of two V-shape clipping boards, a swinging base, a pin, two torsional springs, a positioning board, and so on. The clipping board is connected with the swinging base by the pin, and it can circle around the pin. Two torsional springs crossing the pin are installed on two sides of the clipping board, and they can provide elastic force for clipping mechanism. When modular charges depart from the clipping board by the modular charge pushing device, owning to the preload of the torsional springs, the clipping board will turn into the modular charge storage device. In order to avoid the interference between the clipping board and the pushing board of the modular charge pushing mechanism which finishes the push and returns according to the original schedule, there is a positioning board in a swinging base. When the apophysis part of the clipping board hits the positioning board, the clipping board will stop whirling. thus it provides space for the return of the pushing board.

Fig.3 Composition of modular charge clippling mechanism

1.2 Working principle and composition of modular charge pushing mechanism

The pushing mechanism is responsible for pushing a certain amount of modular charge from the magazine into the reception tray synchronously according to the shooting necessity. When it pushes modular charge, it should be speedy and stable as much as possible, without much preload. The composition of the pushing mechanism is shown in Fig.4.

Fig.4 Composition of modular charge pushing mechanism

The pushing mechanism depends on six spiral transmission modules composed of six sliding blocks, six screws, six guide rails and six pushing boards to achieve the motion that pushes a certain amount of modular charge of storage devic. The six spiral drive modules and the hollow axle of steady pedestal are connected by corresponding transmission gears. Driven by the electric motor of pushing mechanism and reduction gear, the hollow axle rotates and the corresponding pushing board starts to push the modular charge straightly.

The pushing mechanism utilizes the stretch rod to control the motion that pushes a certain amount of modular charge simultaneously only one time. The composition and cross-section view of stretch rod are shown in Figs.5 and 6.

Fig.5 Composition of stretch rod

Fig.6 Cross-section view of stretch rod

Two long key slots that can provide space to allow wedge-shaped key to glide are distributed in the hollow axle symmetrically, and there are six wedge-shaped orifices on the key groove. The stretch rod is composed of six circular and hollow cylinders, and the external part of hollow cylinder is the tray used to install the wedge-shaped key. The mutual connections of circular apophysis 1, circular apophysis 2 and circular concavity make six hollow cylinders form the stretch rod that can go and return successively. The rectangle slot is in the installation tray of the wedge-shaped key, inside of which is the compression spring, and the wedge-shaped key is installed on the compression spring. The six hollow cylinders of stretch rod can go and return successively on the influence of spiral transmission module, electric motor of stretch rod and reduction gear. The spiral transmission module is composed of six pushing boards, two obstructing loops, six guide rods and twelve screws. When the wedge-shaped key of tray glides to the position of wedge-shaped orifice, it can go into the orifice by the force produced by the compression spring. The hollow axle and gear of the hollow axle connect and rotate together on the same shaft under the influence of the wedge-shaped key.

The six wedge-shaped keys are corresponding with six gear transmission modules. The gear module can turn only if the key links with the gear and hollow axle. Other gear modules without key can only turn emptily and cannot transmit power. Therefore, when the stretch rod glides the corresponding position, the pushing mechanism can push a certain amount of module charge out synchronously.

2 Dynamic simulation of feeding mechanism

The three dimensional parts are established and assembled by the master of Ideas, which are changed to thex_tformat of UG by the translator. The entity model is simplified before imported to reduce the number of rigid bodies, and then the number of rectangle arrays can be decreased, so the simulation time can be reduced obviously.

Import the transferred document of three dimensional model into ADAMS[6], and set up material quality for all kinds of parts, use Boolean operation to simplify the parts that have not relative movement to the rigid body, then add the essential motion connection and contact for every part, add the drive module finally.

2.1 Simulation

Figs.7 and 8 are thexaxis andyaxis velocity curves of modular charge storage device when it turns round one cycle in the magazine. Fig.9 is thexaxis displacement curves of modular charge storage device when the pushing board of the pushing mechanism hits modular charge vertically and downwards at different velocities.

Fig.7 X axis velocity curve of modular charge

Fig.8 Y axis velocity curve of modular charge

Fig.9 X axis displacement curve of modular charge

2.2 Analysis

1) From Figs.7 and 8, we can know that when modular charge turns round one cycle in the magazine, the number of velocity pulse is small and the fluctuation frequency of periodicity is low. These advantages are very important to the reliableity of the modular charge feeding mechanism. The polygon effect of chain transmission of the traditional chain slewing magazine makes the frequency of velocity pulse high and the transmission process unstable obviously when the magazine turns round. But the adopted magazine can strengthen the stability when modular charge is transported obviously, thus it is beneficial to enhance the reliability of feeding mechanism.

2) Fig.9 is the part ofxaxis displacement curves of modular charge when the pushing board impact on modular charge at different pushing velocities. Making use of the optimization function of ADAMS to seek the best pushing velocity can guarantee that the push motion is a rapid, stable and low impact force to modular charge. After the optimization, the result shows that if the pushing velocity becomes smaller in 0-150 mm/s, the modular charge displacement variation value ofxaxis will become bigger, so it is easy to cause left and right rocking phenomenon when the modular charge is pushed from the storage device. The stability becomes lower, which is disadvantageous for modular charge to enter into the reception tray accurately. When the pushing velocity exceeds 150 mm/s, the modular charge displacement variation value ofxaxis will be small, so the left and right rocking phenomenon is not obvious, which is advantageous for modular charge to enter into the tray accurately. On condition that the pushing velocity exceeds 150 mm/s, the modular charge displacement variation values ofxaxis are comparatively different velocities. The result shows that the gaps of different displacement variation values are minute. But if the pushing velocity is over high, the instantaneous impact force that acts on the modular charge will also be increased, therefore, the pushing velocity should not be too fast. Based on the above conclusions, the pushing velocity of 150 mm/s is the best choice. At this time the left and right rocking phenomenon is not obvious and the stability is high in the process of the modular charge entering into the tray from storage device.

3) Fig.10 is the modular charge velocity curve in the process of the modular charge entering into reception tray from storage device. The curve shows that modular charge velocity has a sharp rise at the initial stage, that is mainly because there is a certain distance between the pushing board and the modular charge, and the instantaneous impact force on modular charge results in this phenomenon[7-8]. Then the velocity becomes gradually stable, without many fluctuation phenomena, which is advantageous for modular charge to enter into the tray accurately. Then the velocity rises and drops rapidly, that is mainly because modular charge is seperated from the clipping board of storage device by the pushing board, and the inertia force of the pushing board and gravity of modular charge make the velocity rise rapidly. When modular charge enters into the tray, it will produce a collision with the tray, which makes the velocity drop until becoming static gradually.

Fig.10 Velocity curve of modular charge when it is pushed

3 Conclusion

The modular charge feeding mechanism designed in this paper adopts gear drive and spiral drive. It can keep the modular charge stable in the transmission, and enhance the reliability of large caliber howitzer feeding system effectively, which is higher than the traditional chain-transmission. And the pushing modular charge mechanism can push a certain amount of modular charge into the tray synchronously, so that the time is needed fewer than that of pushing modular charges one by one.

The feeding mechanism provides a new idea and method. The idea is reasonable, feasible and practical. At the same time, it also provides reference for the early theory design and later optimization design of other transmission devices, and has high practical guide significance.

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模塊裝藥供藥裝置設計與分析

針對以往鏈式回轉藥倉由于多邊形效應導致的藥倉回轉運動不穩定以及現有的推藥機構不能對模塊藥進行同步推送等缺點， 設計了一種新型供藥裝置。 該裝置能夠對模塊藥實現快速、 平穩地選取并可以將一定數量模塊藥同步推送進接藥盤。 建立了三維模型， 運用ADAMS對供藥裝置進行仿真分析。 結果表明， 該裝置可以快速、 平穩地將模塊藥輸送進接藥盤， 可為以后的實際設計提供理論依據。

模塊藥； 多邊形效應； 供藥裝置； ADAMS； 接藥盤

LIU Hai-gang, WANG Gang, XIONG Sheng, et al. Design and analysis of modular charge feeding mechanism . Journal of Measurement Science and Instrumentation, 2015, 6(3)： 240-246. [

劉海剛， 王 剛， 熊 勝， 劉鵬飛， 張孝忠

(中北大學 機電工程學院， 山西 太原 030051)

10.3969/j.issn.1674-8042.2015.03.007]

LIU Hai-gang (455034168@qq.com)

1674-8042(2015)03-0240-07 doi： 10.3969/j.issn.1674-8042.2015.03.007

Received date： 2015-05-18

CLD number： TJ303 Document code： A