Jaroslav Semen, Sc. D. Eng.., Oleg Semen

Lviv national agrarian university, Ukraine

device for enclosing of trees’ stems during

mechanized removing fruits

 

Оne of the main problems of a low level of horticulture productivity is an insufficient level of introduction of mechanized technologies and devices of picking and transportation of crops [2].

Slow introduction of mechanized technologies into gardening can be explained by the fact that during the machinery operations trees may be damaged in the sites of the transportation of exciting attempts generated by a shaker and distributed by the area of the contact of the closure cushions with a stem. The main reason of the stems damager during the mechanized harvesting is excelling of admissible contact pressures and tangential forces on the bark of tree transmitted through an enclosure [6].

In this regard, the research focused on the development of new devices for enclosing stems with minimal damages during transmission of attempts for high-yielding harvesting of fruits.

To diminish the danger of harmful effects of mechanizet harvesting on the state and productivity of fruit trees different devises are developed. Their construction is forseen to protect the tree’s bark and cambium layer of the extra-normal attempts of defend the root system of bending and breaking the fruits holding branches during fruits taking [7]. The present cushions of enclosure of serial fruit-removing machines are the rubber rectangle parallelepipeds with the thickness of 40 mm. Their surfaces contact with a tree stem. They possess hollow rubbish cylinders with an external diameter of 110 mm and pressed from the inner cavity another hollow cylinder with a high hardness of materials [1]. Such enclosures catch the tree’s stem and transmit in the exciting attempts obligatory for fruits removing rather successfully. But they can never prevent the bark’s crushing and displacement alongside and crosswise of fibres.

The cable vibropercussive machine implements the loop-capture with some peculiarities caused by the peculiarities of its own functioning. The exciting vibrations here are transmitted in a single-sided direction. Therefore, the loop-inclosures are thrown on the tree stem before head. Then it is joined with a vibration exciter a flexible element.

It is know that when the loop-capture interacts with the tree's stem, its bark can accept the normal pressure Рn  and tangential Рtв (alongside of fibres) and Рtп (crosswide the fibres). The pressure is determined by the following formular [5]:

                               (1)

where jzп, jzв – are consequently, coefficients of the contacts of loop- captures with a tree's bark alongside and crosswise the fibres.

Exciting attempts transmitted to trees with bent stems are accompanied with the decrease of normal pressure on the bank Рn to the value which do not guarantee the adequate harvesting:

                                                                  (2)

where  [Р] – is the admissible normal pressure on the bark which can guarantee the adequate norm of fruit picking, МПа.

Tangential pressure  crosswise and alongside the fibres increases proporsionally the angle of stem's bending. This causes crushing and cleaving of the tree's bark. Overcoming of negative impact of the machine's operating elements on the perennial plantations and observing all the abligatory conditions is rather problematic:

,                                              (3)

where  [tп] , [tв] – the admissible pressure on the bark consequently crosswise and alongside the fibres, МПа.

The mechanisn which helped to deminish negative effect of the cable shaker on the tree's bark during fruits removing from the trees with bent stems was the improved loop-capture [3]. The loop-capture is equipped with two elastic bands. Their surfaces of contacts are covered with consistent lubricant. The bands are placed in such a way that the surface of one of them can contact with elastic loop-capture. Another band's surface must contact, then, with a tree's bark.

In such a case, during generations of exciting attempts, a  normal pressure is transmitted  to the  stem through elastic bands with a coefficient of linking jст  which is less of the coefficient of linking the surface of shells with a band as well as the tree's bark with a band.

This condition can be illustrated in such a way:

                                            (4)

The decrease of tangential pressure is quite evident. This causes the interaction of loop-capture with the tree's stem (but without crushing and cleaving its bark its bark alongside and crosswise the fibres). Still, the suggested and construction can solve the problem of cambium layer damage only partly. They do not consider here different damping and hardness abilitles of trees and loop-captures enclosing them. The cable of enclosing used in construction of loop-capture impacts the elastic band mainly in the site of contact where transmission of exciting contacts in special shells is distributed on the area of contact with a tree disproportionally

The given drawback can be liquidated by the suggested llop-capture where the cable is shifted by the rubberized belts 8(Fig.) and 9, which are additionally fixed in the external side of the single elastic base 1 and the tree's stem in the direction of the pointers A and B [4].

Technological process of interaction of adaptive loop-capture with a tree's stem has several stages. The first stage forsees the shell filling with powdering  material any deformatioons. During the proceding tension of a cable the powdering material is distributed in the shells. The powdering material occupies all the unoccupied volumes. Simultaneously, the spot of a contact of adaptive loop with a stem appears together with a rather effective coppyning of the surface unevenness of the tree's bark. The pressure, then, is distributed proportionally on the whole surface of a contact.

The next stage forsees the inclusion of vibroexciter oscilations. The adaptive cushions transmit generative attempts from vibroexciter to the stem. In such a way fruits harvesting takes place.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Powdering material in the shells under the influence of dynamic attempts is thichened. The area of contact is enlarged. As the shell’s filler gets its maximal possible thickness the hardness of loop-capture becomes rapidly encreased.

The given situation causes the maximal efficiency of transmitting exciting attempts of the tree shaker. This, consequently, causes the increase of productivity of fruits harvesting and shortening of the period of oscilations. The proportional distribution of the exciting attempts of the whole area of the spot of the contact with a stem guarantees the decrease of specific pressure on the bark and facilitates the decrease of possible mechanic damages of the trees’ bark and its cambium layer.  

Conclusions. Fruit-removing mechanisms of the cable type may be used in the gardens with spontaneous way of planting. The machines equipment with self-gripping loop-captures may allow to adapt them to the wide diapason of pomological rows of perennial plantations. Their sufficient advantage is a vibro-shocking regime of operations which can protect trees from damages. Such types of machines are now on the stage of development and, therefore, they cannot of utilized by the Ukrainians gardeners.

 

References

 

1.     Драный А.С. Адаптивные захваты штамбовых стряхивателей плодоуборочных машин. Дисс…канд. техн. наук. –Москва, 1997. –192 с.

2.     Интенсивные технологии в садоводстве (пер. с польск. Н.А. Чупеева) –М.: Агропромиздат, 1990. –300 с.

3.     Патент МПК 7А01D 46/26. Петля-захват плодозбиральної машини (Україна) –№2003010681; Заявл. 27.01.2003. Опубл. 15.12.2003. Бюл. №12 –авт. Семен Я.В., Шевчук Р.С., Крупич О.М.

4.     Патент МПК А01D 46/26 (2006/01). Самозатискна петля-захват тросового струшувача (Україна) –№ и 201104710; Заявл. 18.04.2011. Опубл. 10.11.2011. Бюл. №21–авт. Семен О.Я., Семен Я.В., Шевчук Р.С., Крупич О.М., Ріпка І.І., Пришляк О.Ф.

5.     Семен Я.В., Крупич О.М., Пришляк О.Ф. Петля-захват плодозбиральної машини //Міжнародна науково-практична конференція, присвячена 10ій річниці Конференції ООН з питань охорони навколишнього середовища та розвитку “Еколого-економічні проблеми розвитку АПК”. Тези доп. –Львів, 2002. –С. 299-302.

6.     Шевчук Р.С. Допустимые давления на штамбы яблонь при механизированной уборке плодов // Совершенствование механизированных процессов в растениеводстве. – Львовский с.-х. институт, 1986. – С. 57-61.

7.     Шевчук Р.С., Драный А.В. Новые конструкции захватов плодоуборочных машин //Тракторы и сельскохозяйственные машины. –1995. –№11. –С. 34 – 35.