OA18277A - Cocoa husking machine, device used for this purpose. - Google Patents

Description

II PRESENTATION AND DESCRIPTION OF THE COCOA DEBASTER

11.1- GENERAL PRESENTATION OF THE MACHINE

This invention relates to a machine specially designed for simultaneously and safely destroying the hulls of several cocoa pods. This machine has several milling tools regularly arranged on two cylindrical rollers rotating in opposite directions with respect to each other. The cutter tools are sharpened so that they easily penetrate the shell. Their arrangement in staggered rows along the roll ensures simultaneous crushing on several shells. The synchronous interaction of the rollers combined with the penetration of the cutter tools allows the shell to be shredded while preserving the integrity of the beans contained. In the event of a resistant pod, a crumpling step using a helical lug roller was then planned. This machine uses an electric or thermal motor whose power has been estimated at 1.5 kW. The results obtained on a prototype indicate that our sheller is very productive, with an efficiency of over 98% and can crush 90,000 pod shells per day. This thesis briefly reviews the different mechanical podding processes. We then present the essential technical elements of the designed shellfish, solution to user expectations.

11.2- STATE OF THE ART

The processing of cocoa beans into consumable products is preceded by the picking of the pods, podding and drying. These steps each have their own difficulties. We are particularly interested in the podding operation.

Shelling, or de-poding, involves opening the pod in order to extract the cocoa beans. In Cameroon and West Africa, where cocoa cultivation is widespread, this process is still very artisanal, with all the risks of accidents that your cocoa farmers and harvesters run. Several artisanal and scientific trials have been carried out to mechanize cocoa stripping. The review of the literature indicates that four methods are mainly used for podding: manual poding, mechanical lever padding, mechanical shock padding and motorized mechanical padding.

I- Manual poding

This method is the oldest and the most used. The picked pods are broken up with a club or machete. The beans are then easily extracted. Manual poding has certain advantages such as low bean loss, the absence of technical tools to maintain and guaranteed employment for the harvesters. However, although it is very widespread, this method has many drawbacks including slow execution (1500 pods / day on average for an individual), risk of injury to the cocoa beans, exposure of operators to injury and other health risks, etc ...

2- Mechanical poding

Among the solutions proposed is the manual lever machine. This machine offers the advantages of operator finger safety, ease of operation, and easy maintenance. The shortcomings are linked to the difficult setting and maintenance of the pod, the slowness of execution (low efficiency), the operator's energy expenditure. This machine is only very rarely used. A hand operated impact hammer sheller ¹ capable of breaking one to five pods at a time has also been proposed. This machine is of very low efficiency.

Motorized podding machines have also been proposed. The Screw Crusher, for example, takes advantage of the pressure of the grinding screw integral with the gear motor to crush the pod stuck in the hooks fixed on the frame. This embodiment, although easy to implement, has a major drawback including the separation of the beans from the shell crumbs. Furthermore, Messers Christy and Norris ² proposed a machine that requires two operators for its operation: one that fills the hopper with pods are broken by the rotation of a wooden cone fitted with grooves mounted vertically in the crushing cylinder. ; the cylinder also having internal splines. The separation system proved unreliable in addition to the high rate of spoilage of the beans. Mentions also the rotary drum machine ³ in which the pods are crushed. The mixture resulting from the grinding is composed of beans, hull debris and mucilage. This mixture is introduced into a cylinder formed by a mesh screen inside which the separation takes place. The scaler proposed by Nkongho and Endale ⁴ has posed certain problems, namely: the complexity of producing certain shapes, in particular the grinding tank, the risks of jamming, the difficult assembly of the components.

The machines discussed above have had varying success on a local scale, and it is evident that they have not been widely adopted because in many production areas the poding is still manual. Thus, the present invention is intended to be a substantial improvement on known machines which are in use.

¹ Adzimah, SK and Asiam, EK, Design of a Cocoa Pod Splitting Machine, Research Journal of Applied

Sciences, Engineering and Technology vol 2 n ° 7 pp: 622-634,2010 ¹ www.woldcocoafoundation.org of March 05, 2013 ¹ Beyala, Tchouya and Zanfacf "Design of a Cocoa Pod with Rotary Drum" End of thesis studies of the Faculty of Industrial Engineering of the University of Douala, 2011/2012 ⁴ Nkongho Anyi, J. and Endale, Y .: Study and Realization of a Cocoa Ecabosser [ecabo-n] final thesis of ENSET in 2007/2008

Our main goal is to provide a machine to safely destroy cocoa pods, and simultaneously separate the beans from the hulls (debris) by sieving. In addition, this machine should offer the advantage of a small footprint as well as a cost accessible to the "small producer".

11.3- BRIEF DESCRIPTION OF THE INVENTION

This invention relates to a debosser with crushing cutters, a machine specially designed for safely destroying the shell of a cocoa pod. This machine consists of a framework (frame or frame) to be fixed on a "support" surface such as the floor of an agricultural workshop. Casters can be bolted to the base of the frame for easy movement of the machine. An electric or thermal motor for the machine is provided, the motor being fixed to the frame.

II.3.1- Presentation of figures

A further understanding of the present invention can be obtained by decoding the technical drawings relating thereto and contained in Figures 1-20.

Figure 1 is the technological diagram of the operation of the machine.

Figure 2 shows the complete assembly drawing of the invention.

Figure 3-6 shows the definition drawings of the main parts of the machine.

FIG. 7 shows a cross section of the assembly of the 2 rollers-holder milling cutters.

Figure 8 shows the guidance and construction of a milling roller.

Figure 9 shows a longitudinal view of a conveying screw with attached propeller.

Figure 10a is a cross-sectional view of the heavy-duty debris crumpling roller of the pod shell.

Fig. 10b is a further longitudinal view showing the construction of a milling roller.

Figure 11-12 show the drawings of the machine's drive shafts.

Figure 13 is a longitudinal view of the crumpling roller (see also Figure 10b).

Figures 14a-b show the construction and assembly of the machine hopper.

Figure 15-16 represent the modeling and loading of drive shafts

Figures 17-18 are the modeling diagram of the principle of the primer for crushing the pod shell.

11.4- Detailed description of the Machine

This invention relates to a machine specially designed for simultaneously and safely destroying the hulls of several cocoa pods. A characteristic feature of this machine is the use of milling cutters regularly arranged in several rows on cylindrical rollers. Each row of strawberries runs the length of the roll.

FIG. 1 is a technological diagram describing its operation. The motor shaft (5) transmits power to the cutters (4) via a gear (8 * + 8 + l). In their rotational movement in opposite directions and at different relative speeds (or not), the cutter-holder rollers (4) drive and crush the pods introduced into a hopper. Collectively, the cutter rollers provide two portions of cylindrical pod holding surfaces. In this configuration, the rollers rotate in the direction of the space between them, the space towards which the pods being crushed are drawn. Hull debris and beans flow into the primary tank and are entrained by the primary separation screw (6). A primary screen retains some shell debris and allows beans and shell debris of equivalent size to pass to a secondary screen (12). This last sieve retains the rest of the last debris of the hulls and the beans will be evacuated at the bottom. The assembly thus configured allows effective crushing of pods of all sizes.

11.4.1- Motorization characteristics

In this part from the experiments, we determined the breaking energy of a cocoa pod, and consequently the tangential force of the crushing strawberries on the pod, force necessary to open the shell and release the cocoa beans. . This last effort allowed us to assess the stripping torque.

The cutting force on a cocoa pod has been experimentally determined by NKONGHO and Endale ^s as equal to 100N for a rotational speed N = 25 rev / min. Their work also indicates the pressing force F _p (see also figures 20 and 3) necessary to break a pod is of the order of 700 N - 800 N. This result could be refined by the use of an experimental device. precision.

On the other hand Adewumi and Fatusin ⁶ , evaluated the impact energy necessary to break a single pod at 30.9 J. And for 5 pods broken simultaneously, it would take an energy of 78.6 J.

This section presents the choice of an appropriate gear motor for the correct operation of our Cocoa Dehydrator.

11.4.1.1- Total resistive torque (Cr)

Cr = Cr _e + Cr '+ Cr ”

Cr _e : resistant couple due to the cocoa pod.

Cr ’: engine torque in the first separator block.

Cr ”: engine torque in the second separator block.

^s Nkongho Anyi, J. and Endale, Y .: opcit * Adewumi, BA and Fatusin, AB, Design, Fabrication and Testing of an Impact-Type Hand Operated Cocoa

Pod Breaker, Agricultural Engineering International: the C1GR ejoumal. PM 06 022 Vol. VIII, 2006

Couple Cre

Data:

J d _c : diameter of the pod; άς = 120 mm

J d ₂ : cutter diameter.

For a complete turn of the strawberries, they grind n pods;

04 = where C ₄ : pitch circumference of a milling cutter.

d ₄ = - = C * ₄ 152.78. We take: d ₄ = 150mm.

7Γ 7Γ

S 3ο = O | O ₂ = center distance of cutters (2a) and (2b) (see Figures 20 and 3) üo - 200 mm

J distribution of the cutter blades at 45 ° to anyone on the cylindrical surface of the roller.

Figure 20 illustrates the position of the cocoa pod at the start of the strawberry attack.

If we neglect any sliding as well as the mass above the pod, the mechanical actions of the strawberries on the pod are:

Aïf _c and H2 / _c at any point M

Â2 / _c = ί ^Aï / c

(.- ⁴ % slnr cozy and

"% H _{2 / c} sine cosB

Where γ and Θ are respectively the complements of O | O ₂ A and O | O ₂ H (see Figures 20 and 3).

The ranges of variation of the angles γ and Θ with respect to the vertical (O ₂ , y) is:

J 7 <γ <7 with y ₀ = 7, according to the constructive provisions adopted here. 6 2 6 cos y ₀ + H2 / _c cos 0q = 0 following (O ₂ , ÿ) ona: Α _{2 /} = ^ £ ®2.χ77 _{2 /} AN: Â2 / = x 1200 = 927.17N

IC COS / o ^{, c, c} cos 3 (J

Take: j4 ₂ y _f = 927 N

Cr _e = 2 x Â2 / _c xy = ^ 2 / _c xd _{2 (} Cr _e ~ 14 Nm

Couple Cr ’

To put down a "resistant" shell between the corrugated walls of the frame until it breaks if possible, the separation roller (3) must be able to rotate at - W _e and withstand a radial load R = 100 N. (3 ) is wavy and helical and having 9 threads of round profile:

P,: axial pitch = 98 mm

P _v : no propeller; P _v = 9P _X = 882 mm a „: pressure angle; a „= 20 °

P: helix angle β = arctan ^ ² ), β = 35.46 °

Hence d _v : Pitch diameter of the separation screw, d _v = 200 mm ❖ Mechanical actions at I

I am the point of impact.

'F _a = F _M COSCC _n .COSP ^{Ki9 +} / c ^{Ft = F} M ^cosa n- ^sin P ^C Fr = F _M sina _n

These components are expressed in the reference linked to the debris of the hull.

p e

Rs = F _M sina _n hence F _M =

Choice

F _m "429N

F, = 328.4N

From where

F _t = 233.9N

This circuit has 8 impact points.

d _r

The torque is given by: Cr ₂ = 8 F, x - = 4 F, xd _v

Hence: Cr ₂ = 187.1 Nm

Assuming full torque transmission, we have that:

Cr ₂ .W ₂ = Cr'.W _e = * Cr '= Cr ₂

Or W ₂ = | w _e

Thus: Cr '= - x Cr ₄

Hence: Cr ’= 262N.m

Calculation of torque Cr ”

Hypotheses :

J The diameter of the separator and mixer shaft d _2g = 50mm V The force required for mixing is F _m = 100N.

By definition we have:

Cr ”= F _m x which gives Cr” = 2.5 Nm

Calculation of the total resistive torque

Cr = Cr _e + Cr '+ Cr ”which gives Cr = 278.5 Nm

11.4.1.2- Calculation of engine torque

C _m : torque available at the motor output.

η: We neglect the friction in the bearings and we adopt a transmission efficiency of η = 0.70 _ Crû) _r Cmw _m

CrN _r VNm hence C _m ~ 6.63 Nm

Calculation of engine power

Pm = Cm x W _m , which gives P _m = 1041 W

II.4.1.3- Choice of engine

We choose an engine in accordance with the selection rules indicated in the reference by Chevalier ⁷ , its catalog of choice of the LS90L TYPE engine: P = 1.5 kW and N = 1500 rpm.

We will use a reducer of reduction ratio r = À to obtain an operating speed of 25 rpm at the level of the milling cutter-holder shaft.

Π.4.2- Choice of power transmission components ⁷ Chevalier, A .: Industrial designer guide, Hachette Technique, Paris 1981

11.4.2.1- Transmission between the motor and the milling cutter

It is a pulley-belt transmission

Summary of the results • f Type of belt: XPZ

J Pulley diameters: Dj = 100 mm and D ₂₃ = 200 mm

J Belt length: L = 2000 mm

J Real center distance: e _r = 762.9 mm ✓ Number of belts: Nb = 1

J Tension in the taut and slack strands: T = 219.7 N and t = 28.8 N

J Laying tension: T _o = 124.25 N.

11.4.2.2- Transmission between the two milling cutter-holder rollers

It is a straight toothed cylindrical gear transmission

a) Power to be transmitted

P _m = 18.2w = 0.02 KW

C _m = 6.95 Nm

b) Desired center distance: ao = 2OOmm

Pitch diameter of the wheels: d | _Q = 200 mm d | ₉ - - 230 mm.

c) Calculation of the modulus m _n = 1 mm

d) Calculation of the number of teeth

D | 9 = m _n Zi9 which gives Z19 =

e) Calculation of the root and head diameters id _a = 204 mm ld _f = 195 mm

Width of teeth b = km _n which gives b = 20 mm

11.4.2.3- Transmission between the crusher unit and the separator unit

It is a pulley-belt transmission

Summary of results

J Belt type: XPZ

J Pulley diameters: D ₂₃ = 200 mm and D ₁₄ = 280 mm

J Belt length: L - 1600 mm

J Real center distance: e _r = 421.2 mm

J Number of belts: N _b = 1

J Tension in the taut and slack strands: T = 151.7 N and t = 56.2 N ✓ Laying tension: T _o = 103.95 N.

Π.4.2.4- Transmission between the two separation units

It is a pulley-belt transmission

Summary of results

J Belt type: XPB • J Pulley diameters: Du = 280 mm and D | ₄ = 280 mm ✓ Belt length: L = 1600 mm ✓ Actual center distance: e _r = 360.4 mm

J Number of belts: N _b = 1

J Tension in the taut and slack strands: T = 104.1 N and t = 35.9 N

J Laying tension: T _o = 70 N.

Π.4.3- Sizing of the Main Elements of the Scraper

Π.4.3.1- Shafts of Milling Cutters d ₂ = 30 mm.

II.4.3.2- Trees 29

Diameter of the grinding cutter 29

The material used for this shaft is general purpose mild steel, C20 with a _e = 270MPa and a safety factor s = 1.5.

d ₂ 4 = 30 mm

11.4.33- Calculation of Steps

D _m , _n = 26 mm is sufficient for an axis locking.

Calculation of the bearing seat in the housings lc? + R ² N}

Its expression is: P = _2nr2l f

The condition of resistance to matting:

> 12.46 mm; I being the length of the landing.

Choice: Roller bearings in our application must have a range 1 = 15 mm

Choice of bearings

In this study we will choose bearings in C and E (figure 18), B and D (figure 19), for which the dynamic load is equal to C = 152 daN.

Definitive choice of shaft diameter 2

For shaft 2 (figure 2), taking into account variations in cross-section and areas of stress concentration, we choose SKF 6006 bearings with inner ring diameter 030.

Choice of bearings in B and D

C = 259 daN

For shaft 24 (figure 2), taking into account the variations in sections and areas of stress concentration, we choose SKF 6006 bearings with inner ring diameter 030.

11.4.3.4- Key length

The resistance to peeling calculations give 1> 35.3mm.

We choose a standard length that satisfies the conditions and take into account the diameter of the shaft. Taking into account the length of the blade holder hub, we choose the parallel key, form B, 10x8> <40.

11.4.3.5- Cutter Blade Thickness

The blades are embedded by welding in the cutter body (figure 9). These blades work in shear and bending.

• l _a : Length of a blade l _a = 350 mm;

a: Height of a blade a = 10 mm;

: Thickness of a blade;

e> 1.74 mm.

For manufacturing reasons, we will take e = 10 mm.

II.5- Advantages

From the description given above, we can see a number of advantages of our invention:

The need to use dangerous tools such as machetes and knives is eliminated

Safe crushing of pods of all sizes is ensured.

The start-up of this machine is easy, its maintenance easy. It can operate in manual mode (in the absence of electrical or thermal energy).

The use of an engine allows for very high efficiency.

In terms of acquisition cost, this machine is accessible for groups of 3-5 small producers.

Even if the description given here includes certain specificities, these should not be regarded as limitations of this invention, but rather as being exemplary. Indeed, other ramifications and variants can be envisaged. For example, an improvement in the design of this machine, based on the experience of the operation of the prototype produced, could concern the synchronization of the different grinding and separation modules. In addition, the realization of a fully cylindrical screen at the level of the crumpling screw would be just as possible.

Claims (11)

III CLAIMS 1. A machine specially designed to destroy simultaneously and in complete safety the hulls of several cocoa pods and composed of: (a) a framework (frame) intended to be fixed to a support surface and used for placing and maintaining in position the other parts of the machine (b) two milling rollers guided in rotation on the frame and arranged in parallel with a suitable center distance for various pod sizes. (c) particularly shaped and sharpened milling cutters. They are regularly placed on each of the rollers and serve to destroy the shell of the pod. (d) a multi-helical primary separation screw. (e) a single secondary separation screw. (f) two primary and secondary sieves (g) two discharge openings for beans and shell debris. (h) a single motor for three pulley-belt transmissions and one gear transmission. (i) a hopper for protecting and introducing the pods. 2. A machine as specified in claim 1, using a mill holder roller model, milling cutters arranged in staggered rows along the roll and at preferential angles of 45 ° on the circumference, ie 8 rows (Figure 13). 3. A machine as specified in claim 1, the framework of which offers a small footprint for 4 levels of power transmission. 4. A machine as specified in claim 1, in which the motorized roller mill holder is to rotate at a rotational speed of 25 rpm. 5. A machine as specified in claim 2, with crushing cutters shaped, sharpened and sized to easily shred the shell of the pod. 6. A machine as specified in claim 1, for which a single motor is used to control three pulley-belt transmission and a gear transmission without (or with) modification of the speeds of the shafts of the cutter-holder rollers. 7. A machine as specified in claim 1, using a primary separation roller or screw with 9 round profile threads and with a rotation speed set at - the input speed W _e (on the motor cutter-holder roller ). 8. A machine as specified in claim 5 using a primary separation roller or screw to mat a "strong" shell between the corrugated walls of the frame until failure if possible, the separation roller is sized to collect completely. safety a radial load F _R = 100 N. 9. A machine as specified in claim 1, using two primary and secondary sieves ensuring effective separation of beans distinct from that of hull debris. 10. A machine as specified in claim 1, the center distance of the two cutter-holder rolls, the hopper-roller clearances and the inclination of the walls of the hopper ensures grinding of the pod only in the central zone between the rollers. . 11. A machine as specified in claim 5, whose motorization and the dimensions of the crushing rollers make it possible to shell over 90,000 pods per day.