Roller Operator

Author: Chief Editor: Situ Miaoling
Publisher:
Publishing Date: 1999-10-01
Features: This book is a technical training textbook for roller operators, consisting of three parts: basic technical training, intermediate technical training, and advanced technical training. The basic technical training part includes mechanical drawing, mechanical fundamentals, roller construction, and roller operation and maintenance. The intermediate technical training part includes mechanical diesel engine construction and repair, roller electrical equipment, and roller construction and maintenance. The advanced technical training part includes roller operation and repair, as well as road construction and management knowledge. Additionally, this book includes training plans and syllabi for roller operators at the basic, intermediate, and advanced levels. It can serve as a technical training textbook for roller operators' skill level certification and is also suitable for roller operators and maintenance personnel to read and reference.
Excerpt: Divide the angle into three equal parts. 3. Dividing a circle into three and six equal parts Dividing a circle into three and six equal parts can be done using a compass or by combining a triangle ruler with a straightedge (T-square), as shown in Figure 1-11. 4. Dividing a circle into five equal parts Dividing a circle into five equal parts and constructing a regular pentagon can be done using the method shown in Figure 1-12.
(II) Arc Connection
Arc connection refers to smoothly connecting (i.e., tangent) two known line segments (straight lines or arcs) with a known-radius arc. The arc that performs this connecting function is called the connecting arc. To ensure a smooth connection, it is necessary to correctly determine the center of the connecting arc and the tangent point (i.e., the smooth transition point or transition point) of the line segment being connected. Taking the graphical outlines of the connecting rod and wrench as an example in Figure 1-13 to illustrate the method of construction. In the figure, the radius \( R \) of the connecting arc is known, and the positions of the center \( O \) and the tangent points \( A \) and \( B \) need to be determined.
1. Determining the center of the connecting arc
If the radius of the connecting arc is \( R \), the trajectory of the center of the connecting arc is constructed in three cases:
(1) When tangent to a straight line, the center lies on a line parallel to the straight line at a distance \( L = R \) (see Figure 1-13b).
(2) When internally tangent to a circle with center \( O_1 \) and radius \( R_1 \), the trajectory of the connecting arc's center lies on a circle with center \( O_1 \) and radius \( R - R_1 \) (see Figure 1-13a). Similarly, when internally tangent to a circle with center \( O_2 \) and radius \( R_2 \), the trajectory of the connecting arc's center lies on a circle with center \( O_2 \) and radius \( R - R_2 \).
(3) In Figure 1-13b, when externally tangent to a circle with center \( O_1 \) and radius \( R_1 \), the trajectory of the connecting arc's center lies on a circle with center \( O_1 \) and radius \( R + R_1 \). Based on the given conditions, the intersection point of the two trajectories is the center of the connecting arc.
2. Determining the position of the tangent points
The positions of the tangent points \( A \) and \( B \) of the connecting arc are determined in two cases:
(1) When tangent to a straight line, the tangent point is the foot of the perpendicular dropped from the center of the connecting arc to the connected straight line, as shown in Figure 1-13b as point \( B \).
(2) When tangent to an arc externally or internally, the tangent point is the intersection point of the line connecting the centers of the connecting arc and the connected arc (or its extension) with the connected arc, as shown in Figure 1-13a as points \( A \) and \( B \), and in Figure 1-13b as point \( A \). The steps for various types of connections are shown in Table 1-4.
3. General rules for line segment connections
(1) The basic requirement for arc connection is to determine the center of the connecting arc and the connection point (tangent point) between the known arc and the connecting arc.
(2) Arc-to-arc connections can be either internal (tangent) or external (tangent). For external connections, the center is determined using the sum of the radii of the two arcs; for internal connections, the center is determined using the difference of the radii of the two arcs.
(III) Line Segment Analysis and Construction of Plane Geometric Figures
Plane geometric figures are composed of various line segments (straight lines or arcs). Analyzing the dimensions and line segments of a plane geometric figure helps us understand the properties of each line segment in the figure, as well as the dimensions that determine its size and shape. This enables us to master the steps for constructing the figure and the dimensions that should be.