Need help for cam and gears hw

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In summary: The number of teeth for each gear can then be found by multiplying the DP by the pitch diameter. Therefore, for the first gear, N = 3.33*3.33 = 11.11 teeth, and for the second gear, N = 10*3.33 = 33.33 teeth.In summary, the conversation discusses two problems from a homework set - one involving a cam drive for a shoe sewing machine and the other involving the mounting of two gears with a specific velocity ratio. The first problem requires determining the speed of the cam and graphically plotting a displacement diagram, while the second problem involves finding suitable pitch diameters, diametral pitches, and number of teeth for the two gears. The conversation also mentions that
  • #1
whozyourdaddy
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Hi,
I really need help with these two problems from my homework set (got em all done except these two). It would be great if some1 could help me out with this as soon as possible (ESPECIALLY THE FIRST PROBLEM...have no idea how to go about it). Thanks in advance.

A cam drive is used for a mechanism incorporated in a shoe sewing machine. the cam follower motion sequence must be:
1) Rise 0.5in. with cycloidal motion in 0.7sec
2) Dwell for 0.2sec
3) Fall 0.25in. with cycloidal motion in 0.5sec
4) Dwell for 0.2 sec
5) Fall with cycloidal motion in 0.5sec

(A) determine the speed of the cam
(B) graphically plot a displacement diagram

This one i have no idea how to begin or where to go with it.
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Two gears are to be mounted 10 inches apart and have a velocity ratio of 3:1. Find suitable
(A) pitch diameters
(B) diametral pitches
(C) the number of teeth on both gears

This one i think i know.
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  • #2
A) The speed of the cam is determined by the time it takes to complete one cycle (1.9 sec) divided by the circumference of the cam (2πr). So the speed is 1.9/(2πr).B) To graphically plot a displacement diagram, you need to determine the positions of the cam follower at each stage of the motion sequence. This can be done by finding the equation of the cycloidal curves for each movement, and then integrating to find the position at each point in the sequence. Once this is done, you can plot the position of the cam follower as a function of time on a graph.C) For part C, you need to calculate the pitch diameters and diametral pitches of the two gears. The pitch diameter is found by dividing the velocity ratio by the diametral pitch (DP). So for the first gear, the pitch diameter is 10 inches/3 = 3.33 inches. The DP is then found by dividing the number of teeth (N) by the pitch diameter, so N/3.33. For the second gear, the pitch diameter is 10 inches, and the DP is then found by dividing N by 10.
 
  • #3



Hi there,

I can definitely assist you with these problems. Let's start with the first one about the cam drive. To determine the speed of the cam, we need to first calculate the total distance the cam follower needs to travel in the given time frame. Since the cam follower rises 0.5 inches in 0.7 seconds, we can use the formula distance = speed x time to calculate the speed. In this case, the distance is 0.5 inches and the time is 0.7 seconds, so the speed would be 0.5/0.7 = 0.714 inches per second.

To graphically plot a displacement diagram, we can use a graph with time on the x-axis and displacement on the y-axis. We can plot the points for each motion sequence given and then connect them with a smooth curve to represent the cycloidal motion. The dwell periods can be represented by flat lines on the graph.

Moving on to the second problem about the two gears, you are correct in thinking that we need to use pitch diameters and diametral pitches to find the suitable gears. The pitch diameter is the diameter of the imaginary circle that the teeth of the gear would form if they were extended. To find the pitch diameter, we can use the formula pitch diameter = number of teeth/pitch. The velocity ratio of 3:1 means that the smaller gear must have 3 times as many teeth as the larger gear.

As for the diametral pitch, it is the number of teeth per inch of pitch diameter. To find the diametral pitch, we can use the formula diametral pitch = number of teeth/pitch diameter.

Once we have the pitch diameter and diametral pitch, we can then calculate the number of teeth on both gears using the formula number of teeth = pitch diameter x diametral pitch.

I hope this helps you with your homework. Let me know if you need any further clarification or assistance. Good luck!
 

1. What is the purpose of cam and gears in a machine?

The purpose of cam and gears in a machine is to transfer motion from one part of the machine to another in a specific and controlled manner. The cam is a rotating element that converts rotary motion into linear motion, while gears are used to transmit power and change the speed and direction of motion.

2. How do cams and gears work together?

Cams and gears work together by using the cam's irregular shape to push against the teeth of the gear, causing it to rotate. As the gear rotates, it transfers motion to another gear or part of the machine through its teeth. This coordinated movement allows the machine to perform a specific task.

3. What are the different types of cams and gears?

There are various types of cams and gears, each with a specific shape and function. Cams can be classified as follows: disc, cylindrical, plate, linear, and sculptured. Gears can be classified as spur, helical, bevel, worm, and rack and pinion.

4. How are cams and gears designed?

Cams and gears are designed using advanced computer-aided design (CAD) software. Engineers use mathematical equations and simulations to determine the optimal shape and size of the cam and gear teeth for the desired motion and load requirements. Prototypes may also be tested before final production.

5. What are some common applications of cams and gears?

Cams and gears are used in a wide range of machines and mechanisms, including engines, transmissions, conveyor systems, printing presses, and even toys. They are also commonly found in household appliances, such as blenders and washing machines, as well as in industrial equipment like robots and CNC machines.

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