# Analysis and Test of the Tillage Layer Roll-Type Residual Film Recovery Mechanism
## 2 Materials and Methods
### Analysis of the Operation Parameters  
#### 2.2.1 Analysis of Residual Film-Lifting Process  
A film-lifting device is a necessary mechanism for the mechanized recovery of residual film in the plow layer. Its function is to loosen and throw the mixture of film and soil in the plow layer, reduce the soil resistance in the process of picking up residual film, and improve the operational performance of the picking component. During the film-lifting work, the film-lifting knife rotates around the knife shaft and moves in a straight line along with the machine at the same time to achieve the continuous throwing of the plow layer film-soil mixture. To facilitate the recovery operation of the picking device, it is necessary to study the movement of the film-lifting knife and the operation conditions of throwing the film-soil mixture. Point \(O\) is selected as the rotation center of the cutter shaft, a circle with a radius of \(R\) as the rotation radius is drawn, the forward direction of the unit is taken as the \(x\)-axis, the plowing depth direction is taken as the \(y\)-axis, and the xOy coordinate system is established, as shown in Figure 3. In this figure, the film-lifting knife coincides with the \(x\)-axis as the starting position, moves Point \(O\) at the forward speed of \(V_{m}\), rotates at the angular speed of \(\omega\), and connects the moving endpoints to form the absolute trajectory of the film-lifting knife.  
The velocity equation of motion at Point M is:  
\[\left\{\begin{array}{l}v_{x}=V_{m}-R\omega\textit{sin}\omega t\\ v_{y}=R\omega cos\omega t\end{array}\right. \tag{1}\]  
In this formula, \(R\) is the radius of the largest slalom of the film-lifting knife, m; \(V_{m}\) is the machine's forward speed, m/s; \(\omega\) is the rotating angular velocity of lifting blade, rad/s, and \(t\) is the time, s.  
Figure 2: Winding roll structure function. (1, drive shaft head; 2, spring-tooth; 3, square tube; 4, support the shaft head).  
To meet the condition that the film-lifting cutter throws the film-soil mixture backward, the horizontal component velocity \(V_{x}\) of the absolute velocity at any point on the absolute motion trajectory of the film-lifting cutter is less than 0. According to Equation (1), the following can be obtained:  
\[v_{x}=V_{m}-R\omega sin\omega t=V_{m}(1-\lambda sin\omega t)<0 \tag{2}\]  
Equation (2) can be varied as follows:  
\[V_{m}-R\omega(R-h)/R<0 \tag{3}\]  
Moreover, the following is obtained:  
\[V_{m}<(R-h)\omega \tag{4}\]  
After a change is made, we can obtain:  
\[h<R-V_{m}/\omega=R(1-1/\lambda) \tag{5}\]  
Equations (4) and (5) reflect the influence of the change in \(R\), \(\omega\), and \(V_{m}\) on the working depth H. When \(R\) is determined, \(\omega\) and \(V_{m}\) determine the value of \(\lambda\) and the shape of the motion trajectory of the membrane knife. The larger \(\lambda\) is, the larger the maximum chord length value is, which can meet the height requirement of the plowing depth trajectory. According to the index requirements of GB/T 25412-2021 [25] on the operation performance of residual film recycling machine, the film-lifting depth h is taken as 150 mm, the blade of I T225 type is selected, its operation radius is 225 mm, and the forward speed of the tractor is taken as 2.5 km/h. After a calculation is performed, the critical speed of the film-lifting blade that causes the backward throwing of the mixture of film and soil in the plow layer is \(\omega>\) 9.2 rad/s. At this time, \(\lambda>\) 3 is obtained. According to the analysis of the influencing factors, such as film lifting, soil breaking, and power consumption, combined with the design and calculation of the transmission system, the rotating speed \(\omega\) of the film-lifting knife is 22.37 rad/s.