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Paul [167]
3 years ago
5

A NC drill press is to perform a series of through-hole drilling operations on a 1.75 in thick aluminum plate that is a componen

t in a heat exchanger. Each hole is ¾ in diameter. There are 100 holes in all, arranged in a 10 by 10 matrix pattern, and the distance between adjacent hole centers (along the square) = 1.5 in. The cutting speed = 300 ft/min, the penetration feed (z-direction) = 0.015 in/rev, and the feed rate between holes (x-y plane) = 15.0 in/min.
Assume that x-y moves are made at a distance of 0.5 in above the work surface and that this distance must be included in the penetration feed rate for each hole. Also, the rate at which the drill is retracted from each hole is twice the penetration feed rate. The drill has a point angle = 100 degrees.
Determine the time required from the beginning of the first hole to the completion of the last hole, assuming the most efficient drilling sequence will be used to accomplish the job.
Engineering
2 answers:
jekas [21]3 years ago
7 0

Answer:

26.7 min

Explanation:

First, we will find the <u>time required to drill each hole</u>:

  • N = 300 x 12/0.75 \pi = 1527.7 rev/min
  • fr = 1527.7 (0.015) = 22.916 in/min

Formula for <u>distance per hole</u>: 0.5 + A + 1.75

  • A = 0.5 (0.75) tan (90-100 / 2) = 0.315 in
  • Tm = (0.5 + 0.315 + 1.75) / 22.916 = 0.112 min

Now, we will calculate the <u>time required to draw back the drill form hole</u>:

              = 0.112 / 2 = 0.056 min

Time to move between holes = 1.5 / 15 = 0.1 min

For 100 holes, the number of moves between holes = 99

Total time required to drill 100 holes (t):

                       t = 100 (0.112 + 0.056) + 99 (0.1) = 26.7 min

Irina-Kira [14]3 years ago
4 0

Answer:

The answer to the question is;

The time required from the beginning of the first hole to the completion of the last hole, assuming the most efficient drilling sequence will be used to accomplish the job is

26.785 min

Explanation:

The given parameters are

Thickness of plate = 1.75 in

Diameter of each plate = 3/4 in

Number of holes = 100

Holes arrangement = 10×10 square

Distance between adjacent holes = 1.5 in

Cutting speed = 300 ft/min

Penetration feed = 0.015 in/rev

Transverse rate between holes x-y plane = 15 in/rev

Height of movement above work surface = 0.5 in

Retraction speed = 2×penetration speed

Tip angle = 100 °

We therefore have

Cutting speed = pi×D×n

Where

D = Diameter of drill = 3/4 in

n = Rate of revolution of drill

Therefore

300 ft/min = pi×3/4×n

n = 300/(pi×3/4) = 127.32 ft/min

= 1527.8875 in/min

Penetration rate = 0.015 in/rev

Therefore Penetration rate = 0.015 in/rev × 1527.8875 in/min = 22.92 in/rev

Tip angle = 100 °

Height of tip = 0.375/(tan(50)) = 0.31466 in

Total vertical motion of drill =

Plate thickness + Distance of movement above work surface + Height of drill tip

= 1.75 in + 0.5 in + 0.31466 in

= 2.564 in

Speed of penetration motion = (Distance of motion)/time

Time = Distance/Speed

= (2.564 in)/(22.918 in)

= 0.1119 min

Time of retraction = 0.5 × (Time of penetrative motion)

= 0.5 × 0.1119 = 0.05595 min

Total time to move in and out of each hole = 0.05595 min + 0.1119 min = 0.16785 min

Total time to drill 100 holes = 0.16785 × 100 = 16.785 min

Time for transverse motion = 15 in/min

Distance between each hole = 1.5 in

Time for motion between holes = 1.5/15 =0.1 min

Total time for 100 holes = 0.1×100 = 10 mins

Total time for completing the drilling

= 10 + 16.785 = 26.785 min

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Answer:

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Explanation:

given data

specific surface energy = 0.90 J/m²

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to find out

critical stress required for the propagation

solution

we will apply here critical stress formula for propagation of internal crack

( σc ) = \sqrt{\frac{2E\gamma s}{\pi a}}    .....................1

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so now put value in equation 1 we get

( σc ) = \sqrt{\frac{2E\gamma s}{\pi a}}

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( σc ) = 27.396615 ×10^{6} N/m²

so critical stress required for the propagation is 27.396615 ×10^{6} N/m²

6 0
3 years ago
Answer?...................
torisob [31]

Answer:

The correct option is;

c. Leaving the chuck key in the drill chuck

Explanation:

A Common safety issues with a drill press leaving the chuck key in the drill chuck

It is required that, before turning the drill press power on, ensure that chuck key is removed from the chuck. A self ejecting chuck key reduces the likelihood of the chuck key being accidentally left in the chuck.

It is also required to ensure that the switch is in the OFF position before turning plugging in the power cable

Be sure that the chuck key is removed from the chuck before turning on the power. Using a self-ejecting chuck key is a good way of insuring that the key is not left in the chuck accidentally. Also to avoid accidental starting, make sure the switch is in the OFF position before plugging in the cord. Always disconnect the drill from the power source when making repairs.

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Answer:

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Manufacturer’s Recommendations means the instructions, procedures and recommendations which are issued by any manufacturer of the Equipment relating to the operation, maintenance and repair of the Equipment and any revisions to such instructions, procedures and recommendations agreed to by any manufacturer of the Equipment and which are valid at the time such operation, repair and maintenance is being carried out.

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Explanation:

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Natasha2012 [34]

Answer:

Codes for each of the problems are explained below

Explanation:

PROBLEM 1 IN C++:

#include<iostream>

using namespace std;

//fib function that calculate nth integer of the fibonacci sequence.

void fib(int n){

  // l and r inital fibonacci values for n=1 and n=2;

  int l=1,r=1,c;

 

  //if n==1 or n==2 then print 1.

  if(n==1 || n==2){

      cout << 1;

      return;

  }

  //for loop runs n-2 times and calculates nth integer of fibonacci sequence.

  for(int i=0;i<n-2;i++){

      c=l+r;

      l=r;

      r=c;

      cout << "(" << i << "," << c << ") ";

  }

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  cout << "\n" << c;

}

int main(){

  int n; //declared variable n

  cin >> n; //inputs n to find nth integer of the fibonacci sequence.

  fib(n);//calls function fib to calculate and print fibonacci number.

}

PROBLEM 2 IN PYTHON:

def fib(n):

   print("fib({})".format(n), end=' ')

   if n <= 1:

       return n

   else:

       return fib(n - 1) + fib(n - 2)

if __name__ == '__main__':

   n = int(input())

   result = fib(n)

   print()

   print(result)

7 0
3 years ago
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