# Design and Test of Automatic Feeding Device for Substrate Filling
## 2 Structure and Working Principle of the Whole Machine
### Design of Key Components  
#### 2.3.1 Design of Overturning Frame  
The overturning frame constitutes the fundamental component of the whole automatic loading device. Its principal function is to carry the handcart in order to complete the loading operation. It mainly comprises a track wheel, pushrod, splint, and dump handcart fixing mechanism; its structure is shown in Figure 3. In order to facilitate cooperation with the handcart, the overall structure of the overturning frame is designed according to the shape of the handcart, with the angle between the horizontal surface of the overturning frame and the inclined surface being \(120^{\circ}\). A splint is installed on the overturning frame to hold the tilting surface of the handcart. The splint and the handcart fixing mechanism together serve to fix the handcart. The splint is equipped with slotted holes on the side and is mounted on the overturning frame by bolts, thereby enabling the position of the splint relative to the tilting frame to be adjusted. This allows the overturning frame to be adapted to different sizes of handcarts. The overturning frame contains three sets of track wheels, with the names and roles of each track wheel presented in Table 1. The axle of the rear track wheel is connected to the chain via the side plate and is directly connected to the pushrod. Consequently, the traction force of the chain acts on the rear track wheel axle initially, subsequently transferring to the pushrod, which acts on the overturning frame to facilitate its movement along the track. In order for the overturning frame to reach the tilting preset overturning angle, it is necessary for the pushrod to have a specific length. In the context of the overturning motion, the overturning frame can be regarded as a crank slider mechanism. The crank center is the front track wheel center, the connecting rod is the pushrod, and the rear track wheel axle can be regarded as the slider. The coordinate system depicted in Figure 4 illustrates the rotation of the overturning frame from the solid line position to the dotted line position around the origin. Concurrently, the hinge moves from A\({}_{1}\) to A\({}_{2}\), while the slider translates from B\({}_{1}\) to B\({}_{2}\). Figure 2: Scheme of the overturning process. In the process of design, the position of point A\({}_{1}\) (\(x_{\text{A1}}\), \(y_{\text{A1}}\)) is initially established, and subsequently, the coordinates of the position of point A\({}_{2}\) (\(x_{\text{A2}}\), \(y_{\text{A2}}\)) can be determined in accordance with the following equation:  
\[ \begin{pmatrix}x_{\text{A2}}\\ y_{\text{A2}}\end{pmatrix} =R \begin{pmatrix}x_{\text{A1}}\\ y_{\text{A1}}\end{pmatrix}  \tag{1}\]  
where \(R\) is the rotation matrix:  
\[R= \begin{pmatrix}\cos\theta&-\sin\theta\\ \sin\theta&\cos\theta\end{pmatrix} \]  
where \(\theta\) is the angle of rotation of the overturning frame around the origin, \(50^{\circ}\). The slider moves in parallel, and the design angle between the translation track and the \(x\)-axis angle is \(60^{\circ}\). The travel distance (\(b\)) of the slider is designed to be 235 mm; then, the relationship of position points B\({}_{1}\) (\(x_{\text{B1}}\), \(y_{\text{B1}}\)) and B\({}_{2}\) (\(x_{\text{B2}}\), \(y_{\text{B2}}\)) is \begin{table}
\begin{tabular}{c c} \hline
**Track Wheel** & **Function** \\ \hline Guide wheel & Guiding, so the overturning frame can only move along the track \\ Support wheel & Supporting, so the overturning frame will not impact the chain \\ Driver wheel & Driving, so the overturning frame can move \\ \hline \end{tabular}
\end{table} 
Table 1: The name and function of the track wheel. Figure 4: Schematic diagram of overturning motion. Figure 3: Scheme of the overturning frame. (1) Pushrod; (2) front track wheel; (3) splint; (4) support wheel; (5) rear track wheel; (6) handcart fixing mechanism. \[ \begin{cases}x_{\text{B2}}=x_{\text{B1}}-b\cos\frac{\pi}{3}\\ y_{\text{B2}}=y_{\text{B1}}+b\sin\frac{\pi}{3}\end{cases}