Course project "Gearbox synthesis and analysis"

Contents

INTRODUCTION

1. LEVER MECHANISM SYNTHESIS AND ANALYSIS

1.1 Initial data

1.2 Construction of Provisions Plans

1.3 Structural Analysis

1.4 Computer Mechanism Synthesis and Analysis

1.5 Lever Mechanism Analysis

1.6 Kinematic analysis by plan method

1.6.1 Construction of speed plan

1.6.2 Build Acceleration Plan

1.7 Power calculation

1.7.1 Determination of inertial factors

1.7.2 Power calculation of Assur II2 group (4.5)

1.7.3 Power calculation of Assur II2 group (2,3)

1.7.4 Power calculation of I class mechanism

2. FLYWHEEL CALCULATION

2.1 Determination of the listed factors

2.2 Plotting

2.3 Determination of flywheel inertia moment and its dimensions

3. SYNTHESIS AND ANALYSIS OF CAM MECHANISM

3.1 Pusher motion diagrams

3.2 Determining the main dimensions of the mechanism

3.3 Cam Profile Construction

3.4 Construction and analysis of pressure angle graph

4. SYNTHESIS AND ANALYSIS OF GEAR MECHANISMS

4.1 Determination of gear ratio of mechanisms

4.1.1 Calculation of geometric parameters

4.1.2 Construction of engagement

4.1.3 Calculation and Analysis of Face Overlap Factor

4.2 Planetary Transmission Synthesis and Analysis

4.2.1 Planetary transmission synthesis

4.2.2 Kinematic analysis of planetary

mechanisms

4.3 Calculation of required engine power

CONCLUSION

Literature

Annotation.

The design carried out structural and kinematic analysis, as well as serviceability check of the designed lever mechanism, calculation of the flywheel by the given coefficient of non-uniformity, the main dimensions are determined and the cam profile of the cam mechanism is built, synthesis of involute gear engagement with preliminary determination of gear numbers of wheels; synthesis of planetary gear train with preliminary determination of its gear ratio; and kinematic analysis of said transmission in order to verify the correctness of the synthesis.

The solution of these problems made it possible to build a kinematic scheme of the machine unit as a result of the course project.

3.2. Defines the basic dimensions of the mechanism.

The main dimensions of cam mechanisms with a roller pusher are determined based on the conditions for ensuring power operability and minimum dimensions.

Parallel to the axis of the ordinate of the movement diagram, we draw the trajectory t.B. of the pusher, on which, using the movement diagram, the instantaneous positions of the point B are noted (B0,..., B22).

We define the lengths of the segments BiDi for each position of the mechanism. The calculation formula is as follows:

The resulting segments are deposited as follows: the BD segment is deposited in the direction of the pusher speed vector rotated 900 in the direction of the cam angular speed

The ends of the lines (points D0,..., D22) connect a smooth curve.

To ensure power operability and minimum dimensions, the center of the cam is selected at the point of intersection of the line deposited at an angle equal to the maximum angle of pressure from the extreme point in the area of ​ ​ removal, and a straight line drawn from the point D0 at the same angle deposited in the other direction .

We get the radius of the cam, but as you can see from the drawing it is very small in size. For design reasons, that the shaft is quite massive and has a rather large diameter compared to the resulting diameter of the cam, take the center "O" from the permissible zone, and for simplicity of design and construction we take the mechanism central, the eccentricity is 0.

3.3. Creates a cam profile.

Select Scale

1. When you select the cam center position, draw a circle with the cam radius. We set aside the working angle opposite to the rotation, and divide it into 29 parts. We draw radial lines from the center (their position differs by 10 degrees). The intersection points of the lines and the circle denote B0,..., B22.

2. From points B0,..., B22 at the corresponding positions of the axis of the pusher 0,... 22 we put away segments equal to the movements of the pusher in the corresponding positions BiBi. " Points are connected by a curve, which is the theoretical profile of the cam in its work area. In the near-stand section, the theoretical profile is defined by an arc of a circle of radius R0.

3. We build a real cam profile on which the pusher roller rolls.

We select the radius of the roller from the condition

3.4. Draws and analyzes a pressure angle graph.

To plot the pressure angle versus cam position, the ordinate axis needs to scale the pressure angles. Then measure the angles

in the graph for determining the minimum radius of the cam, and mark the points using these values. By connecting points, we get a graph. From this graph it can be judged that within the angles of removal and far standing the graph does not exceed the specified maximum pressure angle: max = 42. And at the angle of return, the graph exceeds the maximum pressure angle.

4. synthesis and analysis of gear mechanisms.

4.1. Synthesis of involute gear engagement.

The gear mechanisms in question are designed to transmit continuous rotational motion from the driving shaft to the driven shaft by means of gear wheels, the teeth of which form at the point of contact a higher kinema of a tic pair.

To construct the tooth profile of the wheel, a curve in the form of an involute is used - it is outlined by any point of the line when it rolls around without slipping along the circle (the line is called the producing one, and the circle is called the main one).

Involute gear transmission based on round wheels has two positive properties:

1. Provides constant gear ratio in the process of turning the wheels (proved using the main engagement theorem).

2. The value of the transfer ratio does not change when the axial distance changes.

The main design parameters of any gear wheel are the number of teeth (z) and the module (m). Each point of the involute tooth profile is characterized by the angles of the tooth profile (y), the value of which on the division circle is standard and equal to y = = 20.

4.1.2. Creates an engagement.

1. For each wheel, an involute tooth profile is built:

Tooth Profile Construction Sequence:

1. On the main circle, we arbitrarily select the initial zero point of the involvent 0.

2. With the constant "solution" of the meter ab (equal to 8... 10 mm), we lay equal segments on the main circle, we get the points 1, "2," 3,..., n. "

3. Through the resulting points, we draw tangents to the main circle along which we lay the segments ab, the number of which at each construction is equal to the point number.

4. Repeat the sketch until the tangent (with the lines ab laid on it) intersects with the vertex circle.

5. By connecting the obtained points 1,2,3,4,..., n we obtain involvent.

6. Half the thickness of the tooth S/2 is deposited along the dividing circle (permissible along the chord) and the axis of the tooth is passed.

7. Symmetrically to the tooth axis, we build its left profile.

8. The original points of involute 0 are connected to the center of the wheel.

9. Circles are drawn from the centers of wheels O1 and O2: dividing, main, tooth depressions, tooth tops.

10. A tooth thickness is deposited on the dividing circle and a left tooth profile is built symmetrically to the right tooth profile.

11. Involute engagement is being built.

4.2.2. Kinematic analysis of planetary mechanisms.

Kinematic analysis consists in determining the gear ratio of a particular planetary mechanism with known numbers of wheel teeth.

Graphoanalytic construction sequence:

A) on an arbitrary scale, a velocity vector (wheel engagement with the satellite) is built and connected to the central axis O - we obtain a line of distribution of wheel speeds to and measure its inclination angle;

B) build the satellite velocity distribution line;

C) determine the velocity vector of the satellite axis and connect it to the central axis, obtain the distribution line of the carrier and its inclination angle to the vertical;

D) determine the gear ratio of the studied planetary mechanism.

Conclusion

Based on the results of individual sheets of the course design, we compile a kinematic diagram of the machine unit with the image of all links and kinematic pairs of individual mechanisms.

The kinematic diagram of the machine unit shows:

1. Engine D with indication of its RPM and required power.

2. Diagram of transfer mechanism PM1 selected during its synthesis with indication of numbers of wheel teeth and number of satellites.

3. Diagram of hinge-lever mechanism with indication of relative parameters (relative lengths of links).

4. Flywheel M with indication of its moment of inertia and main dimensions.

5. Diagram of transfer mechanism PM2 with indication of numbers of teeth of its wheels.

6. Cam mechanism diagram indicating calculated radius of cam washer, roller and eccentricity value.

7. The connection of the motor shaft with the driving shaft of the mechanism PM1 by the clutch M1 is schematically indicated, and the driven shaft of the mechanism PM1 with the crank of the working machine PM is indicated by the clutch M2.

The kinematic scheme is the end result of the course design and contains the initial data for the further design of the machine unit (strength calculations, mechanism design development, etc.).

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