CALCULATION AND DESIGN OF THE WORKING BODY FRUIT AND VEGETABLE CUTTER

ABSTRACT

This article analyzes the device of the fruit and vegetable cutter and theoretical views on their design. The equations used in the improvement of the cutting machine and their proportionality are investigated.

АННОТАЦИЯ

В данной статье анализируется устройство плодоовощерезки и теоретические взгляды на их конструкцию. Исследованы уравнения, используемые при совершенствовании режущей машины, и их пропорциональность.

Keywords: cutting machine, cutting area, grinding process duration, loading volume.

Ключевые слова: машина для нарезки, площадь резки, продолжительность процесса измельчения, объем загрузки.

Fruit slicers are used to cut raw fruits and vegetables into thin layers, regardless of their shape (Fig. 1).

Figure 1. Scheme of a fruit and vegetable cutter: 1-working corps; 2-cover; 3-knife shaft; 4-blade; S is the cross-sectional area of the product layer; S₀ is the surface of the segment formed by the body

As we know, milling machines belong to the class of periodic machines. The products entered into the machine for grinding are transferred to the rotating working body 1. The lid 2 of the case is partially closed for product insertion. The shaft 3 is attached to the body, and the blades 4 are fastened to the shaft. The rotation frequency of the shaft is from 1000 to 3000 min-1, the number of blades is from 3 to 16, the rotation frequency of the working body is taken in the range of 6...20 min^-1 [1].

Milling machines are mainly characterized by the geometric size of the rotating working body . The loading volume of the working body  is equal to the average of 0.5...0.6 of the geometric volume of the container [2, 3].

, m³,                                 (1)

where  is the distance from the axis of rotation of the working body to the axis of the blade shaft;  - the coefficient of filling the volume of the labor force with products;  is the area of the segment formed by the working body.

The efficiency of the slicer is determined as follows:

, m³/s,                                        (2.2)

Where ;  - duration of grinding process, s;   - duration of auxiliary operations, s;

Let's consider the simplest scheme describing the principle of operation of the flat blade cutting mechanism (Fig.2).

Fig.2. Scheme of the cutting mechanism with a flat blade:

1 - hopper; 2 - support plane; 3 - flat blade; 4 - crank-rod mechanism; 5 - output node.

Raw materials are fed into the hopper 1. The bottom of the bunker is located at a distance of 2 h from the base plane. The flat blade 3 is moved back and forth by means of a crank-rod mechanism 4. When the blade is moved to the right, its blade cuts the product layer of thickness h coming out of the hopper. The cut product leaves the machine through the output node 5. Thus, this process is continuously repeated.

Disadvantages [2,3] of this mechanism:

a) the product layer is separated by cutting;

b) the advance-return movement of the blade affects productivity;

d) cutting is done only in one direction, etc.

The advance-return movement of the blade can be replaced by a rotation movement (Fig. 3). For this, the blade 1 is mounted on the rotating disk 2, where the blade is located above the bladed disk, which allows to cut the product layer at the installed height h.

Multiple blades can be installed on the disc, and the performance of the cutting mechanism varies accordingly, depending on the speed of rotation of the disc. In general, its performance can be determined as follows:

, kg/s,                                 (3)

where  is the cutting area (usually taken to be equal to the area of the bottom of the bunker), m²;  - coefficient of use of the cutting power of the mechanism;  - angular speed of the disc, rad/s;  - the number of blades installed on the disk, units;  - cutting height of the product layer, m;  - product density, kg/m³.

Fig. 3. Cutting scheme of cutting machine blades:

1 - blade; 2 - disc; 3 - blade of the knife.

Arbitrary selection of the rotational speed of the disk with knives is not appropriate, because it is calculated based on the free fall time of the product being cut from a height h equal to the distance between the plane of the disk and the blade, i.e.:

, m,                                                      (4)

where  is the descent time, s.

The interval time for the blades to pass through the point of cutting the product is equal to:

, s.                                                   (5)

For the normal operation of the cutting mechanism,  condition must be met:

or

,

In this,

, rad/s.                                               (6)

In practice, taking into account the limited fall of the product into the bunker, then:

, s^-

Through the above equations, a theoretical analysis of cutting machine improvement can be developed. So, after determining the main parameters in the cutting process, it is possible to determine the process acceleration factors.

References:

1. Kachru R.P., Balasubramania D., Nachiket K. C.1996. Design, Development and Evaluation of Rotary Slicer for Raw Banana Chips. Agricultural Mechanisation in Africa,Asia and Latin America, 27(4): 61 – 64.
2. Alekseev G.V., Danilenko E.A. Modeling capabilities chopping food additives for functional foods. Vestnik mezhdunarodnoi akademii kholoda. [Bulletin of International academy of the chill], 2011, no. 2, pp. 16-18.
3. Шапров М.Н., Семин Д.В., Садовников М.А. Качественные показатели работы машины для резания очищенной мякоти плодов бахчевых культур // Аграрная наука - основа успешного развития АПК и сохранения экосистем. Материалы Междунар. науч.-практ. конф. Том 3. - Волгоград: ФГБОУ ВПО Волгоградский ГАУ, 2012.- С.191-195.