Design of a Silent Jackhammer

Topics: Drill, Jackhammer, Gas compressor Pages: 35 (2917 words) Published: March 19, 2014
THE UNIVERSITY OF MANCHESTER

THE SCHOOL OF MACE

MECHANICAL ENGINEERING DESIGN I

SEMESTER 2013-2014

DESIGN OF A SILENT HAND-HELD JACKHAMMER

STUDENT NAME: LENGSHAN WANG

STUDENT ID: 9121060

GROUP 13

COORDINATOR : DR OLUTUNDE OYADIJI LECTURER(S): PROF SRI HINDUJA, DR MOHAMMAD SHEIKH

SUBMISSION DATE: 16/12/2013

ABSTRACT

The present designs relate to a various devices added to the jackhammer or an inner structural change, whose purpose is to reduce the jackhammer's noise when working. In general, there are three types of jackhammers which are air-cycle system jackhammer, jackhammer with air channel composed of unbendable metal, adding an energy-absorbing jacket cover over the housing of the jackhammer and substituting the original material of piston with Mn-Cu alloy. Three different conceptual and embodiment design will be displayed in the report.

JACKHAMMERS WERE ORIGINALLY DEVELOPED FOR THE NEEDS OF MINING, QUARRYING, EXCAVATING , TUNNELING, AND MANY OTHER PERCUSSIONS. THE FIRST PROTOTYPE WAS CREATED IN 1848 BY DR. JONATHAN COUCH (1789-1870) . IN THIS DRILL, THE DRILL BIT PASSED THROUGH THE PISTON OF A STEAM ENGINE. HOWEVER, I N 1850, COUCH'S ASSISTANT, JOSEPH W. FOWLE, OPTIMIZED THE JACKHAMMER BY USING COMPRESSED AIR TO DRIVE THE DRILL BIT, WHICH MAKING THE FIRST TRUE PNEUMATIC JACKHAMMER COME INTO THE WORLD.1. BACKGROUND

DR. JONATHAN COUCH (1789-1870)

A HAND-HELD JACKHAMMER IS TYPICALLY A PERCUSSIVE DRILL COMMONLY POWERED BY COMPRESSED AIR. IT HAS TWO HANDLES ON ONE END AND A CHISEL-LIKE BIT ON THE OTHER THAT RAPIDLY JABS UP AND DOWN TO BREAK UP CONCRETE, ROCK, OR OTHER MATERIALS. INSIDE, IT HAS MANY COMPONENTS SUCH AS PITON, VALUE, ETC. FIG. 1 SHOWS THE INTERNAL STRUCTURE OF A JACKHAMMER. THE TOOL IS CONNECTED TO A SEPARATE D AIR-COMPRESSOR UNIT POWERED BY A DIESEL ENGINE BY A PNEUMATIC HOSE , WHICH HAS TO BE MADE OF ESPECIALLY THICK PLASTIC , CARRIES HIGH-PRESSURE AIR. [1] 2. INTRODUCTION

3. PROBLEM AND DESIGN NEEDS

Although it is a very useful tool, there is still a big problem which is the intolerable noise level it produces. That brings much inconvenience and hearing damage to workmen who use it. Basically , a jackhammer generates over 100 dBA (table 1) which is above of very noisy (fig. 2) when it is working. This project aims to design a silent jackhammer whose noise level is at least 20 dBA less than the current noise level of the original jackhammer.

TABLE 1. NOISE LEVELS OF COMMON EQUIPMENTS

FIG. 2. NOISE LEVELS

4. DESIGN SPECIFICATIONS

4.1 Date acquisition

TABLE 2. CONCEPTUAL REVIEW

Q1. Do you think the jackhammer is the best choice when people need percussive tools?

Agree Neutral Disagree

Q2. Do you think a jackhammer have already affected your normal life?

Q3. Do you think the noise from the jackhammer will do damage to the workmen?
Q4. Do you know the price for a normal jackhammer and is it affordable or not?

Q5. Do you know how many resources there are for the noise of jackhammer.

Q6. Do you think changing the inner structural will optimize the function of noise reduction?

Q7. If changing the material of the components could reduce the noise, which parts and what materials do you think need to be changed?

TABLE 3. SURVEY QUESTIONNAIRE

I found five of my classmates or friends and explained to them the purpose of this survey. They acted as the customer/client, and were surveyed by a satisfaction table. The results is shown in the following:

QUESTIONS

VERY SATISFIED

SATISFIED

DISSATISFIED

DON'T KNOW

OVERALL

Overall, how satisfied are you with the designs of the silent jackhammer?

40%

40%

20%

0%

SPECIFIC DESIGN

STRONGLY AGREE

AGREE

DISAGREE

DON'T KNOW

Design 1

80%

20%

0%

0%

Design 2

0%

20%

20%

60%

Design 3

40%

20%

20%

20%

TABLE 4. DESIGN SATISFACTION SURVEY

4.2 ROLE AS A...


References: [1] Anon. What Is a Jackhammer? wiseGEEK. [online]. Available from: http://www.wisegeek.com/what-is-a-jackhammer.htm [Accessed December 11, 2013].
[2] Anon. INGERSOLL-RAND AIR HAMMER 114G USER MANUAL Pdf Download. [online]. Available from: http://www.manualslib.com/manual/77120/Ingersoll-Rand-Air-Hammer-114g.html [Accessed December 14, 2013].
[3] M.F. Ashby and D. Cebon. MATERIALS SELECTION IN MECHANICAL DESIGN. Engineering Department, Trumpington Street, Cambridge CB2 1PZ, UK. June 8-10 1993.
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