Energy consumption, an possible factor in the

assessment of surface drills quality at beech

wood

Simona-Maria Barbu, Loredana Anne-Marie Badescu

Department of Machines for Wood Industry,

Transilvania University of Brasov,

Jud. Brasov, B-ul Eroilor nr. 29

ROMANIA

s.barbu@unitbv.ro, loredana@unitbv.ro

Abstract - The paper present a new data basis regarding the evolution of the energy consumption to drilling

process at the beech species and the method of determination for this parameter. The analyses of the data

basis show the energy dependence of the quality achieved after drilling process. This dependence

has resulted in a mathematical model regarding the quality evaluation for this process. The researches

represent the results of the project PNII-ID-146/2007 and a chapter from the thesis of PhD student author.

Key-words: - quality, drilling, energy, wood

I. PROBLEM FORMULATION

Power absorbed in the process of drilling wood varies on

hole length processed, sometimes significantly. Following

surface quality obtained is found that and it varies on the

depth, but and on the hole radius. Starting from these

observations, the authors of this paper started to deepen the

researches which led to finding a relationship of dependence

of surface quality parameters obtained on hole length at

drilling wood according to active power, respectively

energy consumption. The research is based on analysis and

processing of data from database obtained after registration

power values and of roughness parameters Rz, Ra and RQ

which characterizing surfaces processed with different

cutting conditions in different sections of beech wood. To

achieve drill holes were used carbide tipped drill with

carbide metals wich have diameters of 8, 10 and 12 mm.

For the analysis has been discussed only cutting with drills

of 8 mm considering that they are used in a higher

percentage.

II. THE EXPERIMENT

A Measuring the power absorbed in the drilling beech wood

process and calculation of consumption of energy.

A.1 . Equipment and materials

Test bench consists of: FUS-22 milling machine, three-

phase transducer active power type 3TPT-79-63215,

MAVOWATT 4 watt, 10 PCS data acquisition board with

Velleman PC connection. (Fig.1, Fig.4)

Transducer (electronic) makes converting active power

absorbed in the circuit of three phase electric motor in a

signal of variation in the voltage 0-10V, which apply at

enter of converter digital analog, 1% accuracy class.

Fig.1 Acquisition board model Velleman K8047 wattmeter

MAVOWATT 4

Within experiments was used a helical drill (Fig. 2)

plated with CMS with cylindrical shaft flattened Ф8 mm

diameter, with two channels, the top angle 2к = 60o and

angle of inclination of the propeller ω = 13o.

Fig. 2 Helical drill

Beech timber specimens with 8-12% humidity, were

cut to size L x l x g=195x 40 x 37 [mm × mm × mm] in

longitudinal section, transverse and radial. (Fig. 3)

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Fig.3 Shape and size of samples

A.2. Method of measuring

Parameters of system of drilling used in experimental

model are: speed of 220 rpm, cutting speed 0.92 m / s and

feed rate u1 = 160 and u2= 250 mm / min at a diameter of 8

mm with deep drilling of 30 mm (tuned to the MU used).

Since the actual ratio of drilling resulting from industrial

practice (v / u) is between 30-40, depending on the actual

cutting speed, it must keep this report and in case the

experimental model. Verification is made introducing in the

relationship v / u experimental values for v and u. After

replacement and transform result an experimental report v /

u = Π • D • n / u = 34.85. Is observed that the value of

experimental ratio is in the range of real values, so is

corresponding to working regim from production

practice.For experimental ratio obtained is will calculated

real speed which is equivalent to the 4173.96 rot/min,

cutting speed real is equal with 1.75 m/s and real feed rate

of 3 m/min respectively 4 m/min. After checking its

veracity working parameters we passed to make holes. On

each samples cut in cross section - radial, transversal -

tangential and longitudinal - tangential were made five

holes. Data recording was done automatically by computer

through acquisition card used. The results were saved in txt

files, this simultaneously generating the power graphs.

Fig.4. Stand for determining the power absorbed at

drilling wood.

B Determining the surface quality at drilling of beech.

B.1 Equipment

Test stand for determining the parameters roughness at

surface processed through drilling wood consists of the

following equipment:

Roughness type SJ-201 produced by Mitutoyo with PC

connection with the area measuring of 350 µm (-200 µm to

150 µm); PC; Software Surftest SJ-201P ver. 3.20 for data

acquisition and data filtering and Kennon Height Gauge.

(Fig.5 )

Fig.5 Stand for determining surface quality obtained

through drilling through measuring parameters Rz, Ra and

the roughness Rq.

Positioning and fixing on vertical of electronic roughness

was done with a height gauge with measurement range by

0-300 mm and 0.01 mm accuracy, equipped with a

mechanism for raising and lowering device at the desired

height. The device has been amended to mounting head

detector of electronic roughness, preserving the accuracy of

0.01.

B 2. Method of measuring

Measuring roughness surface obtained at drilling beech

wood for each hole was made in 8 points, through rotating

the samples with a period T = 45 °. (Fig.6 )

Fig. 6 Scheme (the priciple) to measure roughness surface

inner of holes

For roughness measurements were meets the requirements

of ISO 97. Among the parameters defined by ISO 4287

were selected for analysis Ra Rz, Rq. Wavelength was

chosen l = 0.8 mm; length of assessment contains five base

lengths of the n = 5; filter PC 50 (Gaussian).

In Fig.7 is presented the scheme of measured profile of

roughness .

Fig.7 The scheme for measuring profile of roughness.

This was obtained after using automatic filtering of data

with filter PC 50 (Gaussian) content of software used.

Measurements were centralized in databases that were then

processed and the results were interpreted obtaining

important information that helped to elucidate the matter

investigated.

III. RESULTS AND DISCUSSION

A Results and discussion on measuring the power absorbed

5

6

7

1

8

4 2

3

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Active power and load were measured with active

power transducer and recorded using data acquisition board

Velleman.

Since the output signal was a voltage in the range of 0-

10 V, was needed measuring active power with a watt meter

and establish a factor correction between this value of

tension and power by relationship:

ic VPf /= (1)

where: P is active power, in kW, Vi - value of output signal

(voltage), in V, iar fc – factor of correlation.

The data were statistically processed using Excel. Some

databases obtained are shown in figures 8, 9 and 10 for

power and 12, 13 and 14 for roughness parameters.

a

b

Fig.8 Variation of power and energy consumption obtained

at beech wood drilling.

a.longitudinal-tangential, n=220 rot/min, u1=160mm/min ;

b.longitudinal-tangential, n=220 rot/min u2=250 mm/min

a b

Fig.9 Variation of power and energy consumption obtained

at beech wood drilling.

a. transversal-radial, n=220 rot/min, u1=160mm/min

b. transversal-radial, n=220 rot/min u2=250 mm/min

a b

Fig.10. Variation of power and energy consumption

obtained at beech wood drilling.

a. transversal-tangential, n=220 rot/min,

u1=160mm/min

b. transversal-tangetial, n, n=220 rot/min u2=250

mm/min

B Results and discussion at parameters roughness

measurement

Software Surftest SJ 201 for recording data allowed them

to save Excel files and view primary profiles and of profile

of roughness. (Fig.11)

Fig.11 a. Software interface Surftest SJ 201

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Fig.11 b. Viewing data in Excel

Fig.12 Primary profile and roughness profile at drilling

beech wood in transversal - radial section

n=220 rot/min, u=160 mm/min, P1

Fig. 13 Primary profile and roughness profile at drilling

beech wood in transversal-tangential section, n=220

rot/min, u=160 mm/min, P1

Fig. 14 Primary profile and roughness profile at drilling

beech wood transversal-longitudinal section, n=220 rot/min,

u=160 mm/min, P1

Fig.15. Variation roughness of surface at drilling beech

wood.

In figure 15 authors presents the averages for parameters of

the surface

IV CONCLUSIONS

Analyzing the curve of variation of the power P1 to the

beech wood drilling on transversal-radial direction with n =

220 rpm, u = 160 mm / min, while variations roughness on

the length of hole, on the same sample, can be observed that

the roughness profile have a significant variation exactly in

the variation area of the maximum power.

Fig. 16.Variation curves of power (P) and roughness (Rz) at

drilling beech wood in transversal-radial direction (n=220

rot/min, u=250 mm/min, hole 1)

This observation, which is similar for all processing is

justification of authors for the decision to find and the write

a relationship to express dependency between power and

roughness.

Thus, after processing data, the power can be expressed by a

regression equation of polynomial type of degree 6 with

dispersion coefficient of 0.8389 (R2 = 0.8389) of the form:

P = -3•10-16

x6 + 6•10

-13x

5 - 5•10

-10x

4 + 10

-07x

3 - 10

-05x

2 +

0.0001x + 0.4443

Where x represent feed speed,

P = -3•10-16

u6 + 6•10

-13u

5 - 5•10

-10u

4 + 10

-07u

3 - 10

-05u

2 +

0.0001u + 0.4443

for roughness were found three equations depending of the

feed rate which are of the form:

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Rz = 0,022x6 -0,2208x

5 – 2,3841x

4 +41,301x

3 – 196,97x

2 +

362,48x – 185,65

Coefficient of dispersion R2 = 0,9973 (measured at length

H1 in the deep hole)

Rz = 0,114x6 -2,7136x

5 +23,847x

4 -93,483x

3 + 151,65x

2 -

56,672x – 6, 6888

Coefficient of dispersion R2 = 0,8206 (measured at length

H2 in the deep hole).

Rz= 0,0482x6 -1,0722x

5 +8,2946x

4 -23,841x

3 + 1,8956x2 +

82,748x – 49,639

Coefficient of dispersion R2 = 0, 8874 (measured at length

H3 in the deep hole)

Dependence between time and length is of the form:

v=l/t where v is traversing speed of detector (v=0, 5 mm/s),

and l is the distance from which to measure roughness

(l=0,8mm). Replacing for the maximum area will result:

t=0, 8/ 0, 5 => t=1, 6 s

Time measurement of power:

If it replaced x =f(P) from first ecuation with x from second

ecuation will result a equation of form:

Result equation of dependence:

Rz=F (P)

Equation can be generalized and used to estimate the quality

of processed surface through drills depending on power

consumption.

REFERENCES:

[1]Badescu,L, (2001) Modelarea si optimizarea proceselor

prin aschierea lemnului, Ed Info-market Brasov ISBN

973-8204-07-0

[2]Badescu, L.,Barbu, S.,(2005) - Aspecte privind defectele

care apar la burghierea strapunsa a panourilor pe baza

de lemn cu burghie elicoidale si burghie cu varf de

centrare si dinti trasori, Conferinta nationala Stiinta si

ingineria lemnului in mileniul III,vol. I, Editia a VI-a,

Brasov, 4-6 noiembrie 2005, ISBN 973-635-599-3,

p.251-258.

[3]Popa, V., Contributii la dezvoltarea manipulatoarelor si

robotilor pentru industria mobilei, Teza de doctorat,

1999.

[4] SR EN ISO 11562. Specificatii Geometrice pentru

Produse. Starea suprafetei: Metoda profilului –

Caracteristici metrologice ale filtrelor cu corectie de

faza, 1999.

[5] SR ISO 4287 Specificatii Geometrice pentru Produse.

Starea suprafetei: Metoda profilului – Termeni, definitii

si parametri de stare a suprafetei.

[6]Surface roughness tester SJ-201, User’s manual,

Mitutoyo

Acknowledgement

This work was supported by CNCSIS UEFISCSU Project

number PN II- IDEI 146/2007.

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