CN108062905B - Comprehensive demonstration teaching aid for mechanism - Google Patents

Abstract

The invention discloses a mechanism comprehensive demonstration teaching aid which comprises a vertical plate, a bottom plate, an angle code, a crank, a support, a transmission shaft, a gear mechanism, a cam mechanism and a connecting rod mechanism. The eccentric disc is a driving unit of the cam mechanism and the connecting rod mechanism. The cam mechanism comprises a swing rod and a return spring. The connecting rod mechanism comprises a connecting rod a, a connecting rod b, a pin shaft a, a pin shaft b and a pin shaft c. And the crank is rotated, the eccentric disc is driven through the transmission of the transmission shaft and the gear mechanism, then the motion rule of the swing rod is observed, and the swing rod can be in high-pair contact with the eccentric disc through the reset spring. Due to the movement of the eccentric disc, different types of connecting rod mechanisms can be obtained by changing the positions of the pin a, the pin b and the pin c, and different types of movement rules of the connecting rod b can be observed. The invention cultures the learning interest of students through the physical demonstration, improves the teaching quality of the class and achieves the ideal teaching purpose.

Description

A comprehensive demonstration teaching aid for institutions

Technical field

The invention relates to a teaching tool, which is suitable for the intuitive demonstration of mechanism synthesis based on mechanical design. Through the teaching tool, the concepts of high, deputy and low generation, the concept of emergency return characteristics, the concept of dead center and various mechanism synthesis and motion principles can be physically demonstrated. .

Background technique

With the advancement of the reform of innovation and entrepreneurship education in colleges and universities and the need to cultivate innovative talents under new forms, classroom education must change the previous teaching model that emphasizes knowledge infusion and neglects the cultivation of innovative thinking abilities. As one of the basic majors in the mechanical major, many course contents are closely related to engineering practice. An effective way to improve students' innovative thinking ability is to demonstrate physical models in the classroom. In this way, it not only establishes a connection with the theoretical knowledge in the course, but also has strong intuitiveness. Students will feel novel about it and the teaching effect will be better.

However, as a backbone technical basic course for mechanical majors, most schools use multimedia teaching methods to teach basics of mechanical design. In this course, the concepts of high and low generation, the concept of emergency return characteristics, the concept of dead center and various Because mechanism synthesis and motion principles are relatively abstract, it is easy for students to find it difficult to understand if they only understand them conceptually. Therefore, in the classroom, it is particularly important to intuitively observe, operate and compare the comprehensive demonstration teaching aids of an institution to gain a deeper understanding of the course content.

Contents of the invention

In view of the shortcomings of the existing technology, the present invention proposes a mechanism comprehensive demonstration teaching aid. This teaching aid has a simple structure and is easy to assemble. With one model, it can not only demonstrate the concepts of high and low generation, the concept of emergency return characteristics and the concept of dead center, but also observe the working principles of cam mechanisms, link mechanisms and gear mechanisms. It can also Through simple operations, the motion characteristics of different types of link mechanisms can be obtained and the transferability of motion can be understood.

A comprehensive demonstration teaching aid for a mechanism, which includes a vertical plate 9, a bottom plate 10, a corner code 11, a rocker 1, a support 2, a transmission shaft 3, a gear mechanism 4, a cam mechanism and a connecting rod mechanism. The eccentric disk 5 is the driving unit of the cam mechanism and the linkage mechanism.

The cam mechanism includes a rocker 6 and a return spring 13 .

The link mechanism includes connecting rod a7, connecting rod b8, pin a121, pin b122 and pin c123.

The vertical plate 9 is vertically fixed on the base plate 10 through the corner code 11, the support 2 is vertically fixed on the base plate 10, the crank 1 is connected to the gear mechanism 4 through the transmission shaft 3; the transmission shaft 3 is installed on the support 2; the gear Mechanism 4 is composed of gear a401 and gear b402. The transmission shaft 3 is the central axis of gear a401. Gear a401 and gear b402 mesh; the central axis of gear b402 is installed at the eccentricity of the eccentric disk 5; gear a401 and gear b402 are installed on On the back of the vertical plate 9, the eccentric disk 5 is installed on the front of the vertical plate 9; a pin a121 is installed on the eccentric disk 5, one end of the swing rod 6 is connected to the eccentric disk 5 through the pin a121, and the other end of the swing rod 6 is connected to the eccentric disk 5 through the pin a121. One end is connected to the connecting rod b8 through the pin b122; the connecting rod b8 and the connecting rod a7 are installed on the vertical plate 9 through the pin c123; the other end of the connecting rod a7 is in contact with the circumference of the eccentric disk 5. A return spring 13 is provided between the connecting rod a7 and the center of the vertical plate 9 .

The swing rod 6, connecting rod a7, and connecting rod b8 are provided with a plurality of parallel pin mounting holes, and the respective pin mounting holes are evenly arranged in parallel.

The eccentric disc 5 is provided with a plurality of evenly distributed pin mounting holes.

The rocker 1, support 2, swing bar 6, vertical plate 9, and bottom plate 10 are all made of acrylic plates.

Turn the rocker 1. The eccentric disk 5 is driven by the transmission of the transmission shaft 3 and the gear mechanism 4. Then the movement pattern of the pendulum 6 is observed. Through the return spring 13, the pendulum 6 can interact with the eccentric disk. 5 high vice contacts. At the same time, due to the movement of the eccentric disk 5, by changing the positions of the pin a121, the pin b122 and the pin c123, different types of link mechanisms can be obtained, and different movement patterns of the connecting rod 8 can be observed.

By observing the movement of the gear mechanism 4, the working principle of the gear mechanism can be grasped; by observing and comparing the movements of the cam mechanism and the linkage mechanism, the concept of high pair and low generation can be grasped; by observing the movement of the linkage mechanism, the emergency return can be observed The conditions for the generation of characteristics and the concept of mastering the snapback characteristics.

If you rotate the connecting rod 8, by observing the movement of the link mechanism, you can observe the conditions for dead center generation and grasp the concept of dead center.

During the transmission process, the structure of the transmission shaft 3, the bearing, the key connection and the spring 13 can be observed.

Compared with the prior art, the present invention has the following advantages:

First, the present invention complies with the direction of modern higher education reform and can realize a teaching model that values efficiency, interest orientation, and is interesting and intuitive.

Second, the present invention is a multi-purpose thing that creatively integrates multiple mechanisms. It can not only transform the originally abstract and difficult-to-understand principles such as the concepts of high and low generation, the concept of emergency return characteristics, and the concept of dead center through physical demonstration. It is simple and easy to understand, and through simple operations, the mechanism can be converted and the comparison of different motion patterns can be achieved by changing the length of each rod. At the same time, the transmission of mechanical motion can also be observed, thus cultivating students' interest in learning and improving Improve the quality of classroom teaching and achieve the ideal teaching purpose.

Third, the present invention has a simple structure, low cost, easy portability, easy disassembly and assembly, flexible application, convenient use and operation, and has great market promotion value.

Description of drawings

Figure 1 is a front three-dimensional view of the overall structure of the present invention.

Figure 2 is a three-dimensional rear view of the overall structure of the present invention.

Figure 3.1 is a schematic diagram of the instantaneous high-to-low-generation mechanism conversion of the present invention.

Figure 3.2 is a schematic diagram of the high-to-low-generation mechanism conversion in position two of the present invention.

Figure 4 is a comparative schematic diagram of different link mechanisms of the present invention, (a) crank rocker mechanism; (b) double rocker mechanism.

Figure 5.1 is a schematic diagram of the emergency return characteristics of the crank-rocker mechanism of the present invention at the extreme position.

Figure 5.2 is a schematic diagram of the emergency return characteristics of the crank-rocker mechanism of the present invention at the limit position 2.

Figure 5.3 is a schematic diagram of the emergency return characteristics of the double rocker mechanism of the present invention at the extreme position.

Figure 5.4 is a schematic diagram of the emergency return characteristics of the double rocker mechanism in extreme position 2 of the present invention.

Figure 6.1 is a schematic diagram of the dead center characteristics of the crank rocker mechanism at the extreme position of the present invention.

Figure 6.2 is a schematic diagram of the dead center characteristics of the crank-rocker mechanism in extreme position 2 of the present invention.

Figure 6.3 is a schematic diagram of the dead center characteristics of the double rocker mechanism at the extreme position of the present invention.

Figure 6.4 is a schematic diagram of the dead center characteristics of the double rocker mechanism in extreme position 2 of the present invention.

Figure 7 is a three-dimensional modeling diagram of the rocker handle of the present invention.

Figure 8 is a three-dimensional modeling diagram of the eccentric disk of the present invention.

Figure 9 is a three-dimensional modeling diagram of the gear of the present invention.

Detailed ways

The invention proposes a mechanism comprehensive demonstration teaching aid. This teaching aid has a simple structure and is easy to assemble. With one model, it can not only demonstrate the concepts of high and low generation, the concept of emergency return characteristics and the concept of dead center, but also observe the working principles of cam mechanisms, link mechanisms and gear mechanisms. It can also Through simple operations, the motion characteristics of different types of link mechanisms can be obtained and the transferability of motion can be understood.

The present invention will be further described below in conjunction with the accompanying drawings, but the present invention is not limited to the following examples.

As shown in Figures 1 and 2, a comprehensive mechanism demonstration teaching aid includes a vertical plate 9, a bottom plate 10, a corner code 11, a rocker 1, a support 2, a transmission shaft 3, a gear mechanism 4, a cam mechanism and Linkage. The eccentric disk 5 is the driving unit of the cam mechanism and the linkage mechanism.

The cam mechanism includes a rocker 6 and a return spring 13 .

The link mechanism includes connecting rod a7, connecting rod b8, pin a121, pin b122 and pin c123.

The vertical plate 9 is vertically fixed on the base plate 10 through the corner code 11, the support 2 is vertically fixed on the base plate 10, the crank 1 is connected to the gear mechanism 4 through the transmission shaft 3; the transmission shaft 3 is installed on the support 2; the gear Mechanism 4 is composed of gear a401 and gear b402. The transmission shaft 3 is the central axis of gear a401. Gear a401 and gear b402 mesh; the central axis of gear b402 is installed at the eccentricity of the eccentric disk 5; gear a401 and gear b402 are installed on On the back of the vertical plate 9, the eccentric disk 5 is installed on the front of the vertical plate 9; a pin a121 is installed on the eccentric disk 5, one end of the swing rod 6 is connected to the eccentric disk 5 through the pin a121, and the other end of the swing rod 6 is connected to the eccentric disk 5 through the pin a121. One end is connected to the connecting rod b8 through the pin b122; the connecting rod b8 and the connecting rod a7 are installed on the vertical plate 9 through the pin c123; the other end of the connecting rod a7 is in contact with the circumference of the eccentric disk 5. A return spring 13 is provided between the connecting rod a7 and the center of the vertical plate 9 .

The swing rod 6, connecting rod a7, and connecting rod b8 are provided with a plurality of parallel pin mounting holes, and the respective pin mounting holes are evenly arranged in parallel.

The eccentric disc 5 is provided with a plurality of evenly distributed pin mounting holes.

The rocker 1, support 2, swing bar 6, vertical plate 9 and bottom plate 10 are all made of acrylic plates.

Turn the rocker 1. The eccentric disk 5 is driven by the transmission of the transmission shaft 3 and the gear mechanism 4. Then the movement pattern of the pendulum 6 is observed. Through the return spring 13, the pendulum 6 can interact with the eccentric disk. 5 high vice contacts. At the same time, due to the movement of the eccentric disk 5, by changing the positions of the pin a121, the pin b122 and the pin c123, different types of link mechanisms can be obtained, and different movement patterns of the link b8 can be observed.

By observing the movement of the gear mechanism 4, the working principle of the gear mechanism can be grasped; by observing and comparing the movements of the cam mechanism and the linkage mechanism, the concept of high pair and low generation can be grasped; by observing the movement of the linkage mechanism, the emergency return can be observed The conditions for the generation of characteristics and the concept of mastering the snapback characteristics.

If you rotate link b8, by observing the movement of the link mechanism, you can observe the conditions for dead center generation and grasp the concept of dead center.

During the transmission process, the structure of the transmission shaft 3, the bearing, the key connection and the spring 13 can be observed.

As shown in Figure 3.1 and Figure 3.2, it demonstrates the transformation of concepts and institutions between high, deputy and low generations. The cam rocker mechanism has been transformed into a four-bar mechanism through the upper and lower generations. The degree of freedom of the front and rear mechanisms is exactly the same as the instantaneous speed and instantaneous acceleration of the mechanism.

As shown in Figure 4, two linkage mechanisms obtained by changing the length of the rod and connecting and fixing them with pins are demonstrated.

As shown in Figure 5.1-5.4, the conditions for the generation of snapback characteristics and the concept of snapback characteristics are demonstrated. Figure 5.1-5.2 demonstrates the crank rocker mechanism at the extreme positions of the two rockers, explaining the concept of snapback characteristics; Figure 5.3-5.4 demonstrates that the double rocker mechanism has no snapback characteristics during the entire movement.

As shown in Figure 6.1-6.4, the conditions for producing dead center characteristics and the concept of dead center are demonstrated. With connecting rod b8 as the active part, Figure 6.1-6.2 demonstrates that the crank rocker mechanism is at the extreme position of the two rockers, and the crank has a dead center position; Figure 6.3-6.4 demonstrates the entire motion process of the double rocker mechanism There is no dead center position.

As shown in Figure 8, the eccentric disc 5 is provided with a pin mounting hole a501 and a plurality of evenly distributed pin mounting holes b502. The pin mounting hole a501 is an eccentric circular mounting hole, and the layout of each pin mounting hole b502 is: T-shaped.

The rocker is the part held by the hand during demonstration, and is a hexagonal prism with an equivalent diameter of 8mm, a length of 18mm, and a movable diameter of the handle of 30mm. The size of the support is 20mm × 10mm × 70mm. The transmission shaft is a stepped shaft equipped with a deep groove ball bearing with an inner diameter of 4mm and an outer diameter of 8mm with a sealing ring. One end of the shaft is connected to the cradle and the matching bearing The base hole system is installed on the support, and the other end matches the bearing base hole system and is installed in the through hole of the vertical plate.

The gear mechanism is a transmission mechanism, which uses two spur gears with an index circle diameter of 60mm, a module of 1mm, and a tooth number of z=60, arranged up and down. The cam mechanism includes an eccentric disc, a swing bar and a return spring. The diameter of the eccentric disc is 70mm. The center of rotation is 20mm away from its geometric center. It is fixed with the upper gear using bolts, and its surfaces are deviated from each other. There are 3 through holes engraved at the geometric center of 20mm, 40mm and 60mm. The length of the swing rod is 70mm, with five equally spaced through holes carved on one end and one through hole carved on the other end. The return spring is a tension spring with a smaller stiffness coefficient, with a spring wire diameter of 0.8mm, a spring major diameter of 6mm, and a length of 50mm. One end of it is fixed on the swing bar, and the other end is fixed on the vertical plate.

The connecting rod mechanism is based on the eccentric disk, adding a short rod and a long rod. The length of the short rod is 70mm, with three equidistant through holes engraved on one end and one through hole on the other end. The length of the long rod is 180 mm, with five equally spaced through holes engraved on one end and one through hole engraved on the other end. One end of the multiple holes on the short rod and one end of the multiple holes on the long rod are fixed together through a pin. The other end of the short rod is fixed at the center of rotation of the eccentric disk. The other end of the long rod and one end of the swing rod are fixed together through a pin. It is fixed on the vertical plate, and the distance between the fixed point and the rotation center of the eccentric disk is 150mm.

Claims (1)

1. The utility model provides a mechanism synthesizes demonstration teaching aid which characterized in that: the demonstration teaching aid comprises a vertical plate (9), a bottom plate (10), an angle code (11), a crank (1), a support (2), a transmission shaft (3), a gear mechanism (4), a cam mechanism and a connecting rod mechanism; the eccentric disc (5) is a driving unit of a cam mechanism and a connecting rod mechanism;

the cam mechanism comprises a swing rod (6) and a return spring (13);

the connecting rod mechanism comprises a connecting rod a (7), a connecting rod b (8), a pin a (121), a pin b (122) and a pin c (123); the vertical plate (9) is vertically fixed on the bottom plate (10) through the corner brace (11), the support (2) is vertically fixed on the bottom plate (10), and the crank (1) is connected with the gear mechanism (4) through the transmission shaft (3); the transmission shaft (3) is arranged on the support (2); the gear mechanism (4) consists of a gear a (401) and a gear b (402), the transmission shaft (3) is a central shaft of the gear a (401), and the gear a (401) is meshed with the gear b (402); the central shaft of the gear b (402) is arranged at the eccentric position of the eccentric disc (5); the gear a (401) and the gear b (402) are arranged on the back surface of the vertical plate (9), and the eccentric disc (5) is arranged on the front surface of the vertical plate (9); a pin shaft a (121) is arranged on the eccentric disc (5), one end of the swing rod (6) is connected with the eccentric disc (5) through the pin shaft a (121), and the other end of the swing rod (6) is connected with a connecting rod b (8) through a pin shaft b (122); the connecting rod b (8) and the connecting rod a (7) are arranged on the vertical plate (9) through a pin shaft c (123); the other end of the connecting rod a (7) is in contact with the circumference of the eccentric disc (5); a return spring (13) is arranged between the connecting rod a (7) and the center of the vertical plate (9); a plurality of parallel pin shaft mounting holes are formed in the swing rod (6), the connecting rod a (7) and the connecting rod b (8), and the pin shaft mounting holes are uniformly arranged in parallel;

a plurality of pin shaft mounting holes which are uniformly distributed are arranged on the eccentric disc (5);

the crank (1), the support (2), the swing rod (6), the vertical plate (9) and the bottom plate (10) are all made of acrylic plates.