Forajul roto-percutant constituie o metoda rapida de realizare a forajului in roci dure si uscate. Desi acest procedeu este destul de raspandit pe plan mondial, in Romania sunt cunoscute putine aplicatii. Lucrarea se ocupa de modul de utilizare a rezultatelor obtinute de autor pe modele experimentale la constructia unor variante industriale, folosind teoria similitudinii.
Down the hole hammer drilling is a quick way to achieve drilling in hard and dry rocks. Although this process is widespread worldwide, in Romania are known few applications. The paper deals with how to use the results obtained by author in experimental models in the construction of industrial versions, using similarity theory.

Aspects concerning the design of pneumatic drilling engines

In lucrarea de fata se prezinta modul cum se comporta in exploatare rolele de rezemare si cele de garda din componenta grupurilor de reazem ale cuptoarelor cu tambur rotativ. Se prezinta, de asemenea, influenta asupra functionarii acestor elemente a preciziei executiei, montajului si reglarii lor.
In this article is presented the operating behavior of supporting and guard rollers of rotary kilns supports. Also, is presented the influence of precision of the fabrication, montage and adjustment on operating behavior of these elements.

Operating behavior of rotary kilns supports I. The behavior of supporting rollers and guard rollers

In prima parte a lucrarii s-a prezentat comportarea in functionare a rolelor de rezemare si a celor de garda din componenta grupurilor de rezemare a tamburului cuptoarelor rotative. In lucrarea de fata se prezinta comportarea in exploatare a bandajelor utilizate pentru rezemarea acestor cuptoare.
In the first part of the article it was presented the operating behavior of supporting and guard rollers of rotary kiln supports. In this work is presented the operating behavior of the live-rings (tyres) of rotary kiln supports.

Operating behavior of rotary kilns supports I. The behavior of live-rings (tyres)

Operatorii de excavatoare sunt deosebit de expusi la vibratii transmise sistemului mana-brat. Aceste vibratii pot provoca multiple tulburari vasculare, neurologice si musculo-scheletale, in general numit sindromul vibratii mana-brat. Nivelurile de vibratii au fost masurate in trei conditii de lucru si anume relanti, transport si excavare. Nivelul vibratiilor pe manere a fost masurat si analizat si s-a obtinut spectrul de frecvente pentru conditiile de lucru alese. Valorile totale ale vibratiilor in gol, la transport si excavare au fost 3.35, 4.98 si respectiv 5.81m/s2. Rezultatele au aratat ca 10% dintre lucratori sunt expusi la riscul aparitiei sindromului „deget alb” la maini la o perioada de expunere relativ scurta (3-4 ani), in cazul unui program de 8 ore/zi la excavare si la transport pentru incarcare completa . Avand in vedere criteriile de ISO 2631/1997, durata zilnica a timpului de lucru cu excavator ar trebui limitata in scopul de a proteja operatorul, iar programele de munca ar trebui sa includa si perioade de repaus.
The operators of the excavators are especially exposed to hand-arm transmitted vibrations. These vibrations can cause the complex of vascular, neurological and musculoskeletal disorders, collectively named hand-arm vibration syndrome. The vibration levels were measured in three excavator's working conditions, namely idling, transportation and excavation. The vibration level on the handles was measured and analysed and the frequency spectra for the chosen working conditions were obtained. The vibration total values in idling, transportation and excavation were 3.35, 4.98 and 5.81m/s², respectively. Results showed that the 10% of workers are exposed to a risk of vibration-induced white finger disorder of the hands after relatively short periods (3–4 years), if the excavator is used 8 hour per day in excavation and transportation at full load. Considering the criteria of the ISO 2631/1997, the daily working time with the excavator should be limited in order to protect the operator and work schedules should be arranged to include vibration-free periods.

The effects of vibration on operators of excavators

In aceasta lucrare se prezinta o metoda de calcul a parametrilor de lucru a instalatiilor de forat galerii orizontale. Realizarea galeriei se obtine folosind un cap taietor pe care sunt dispuse intr-o anumita succesiune rolele taietoare. Dupa prezentarea mecanismului de dislocare a rocii se calculeaza parametrii regimului de lucru. Determinarea momentului de torsiune si a fortei de apasare a capului taietor se realizeaza in funtţie de dimensiunile amprentei rolei taietoare pe suprafata de lucru.
This paper presentis a calculeitig method for the working parameters of the drilling units for horizontal galleries. The acomplishment of the gallery it is obtained using a cutting head on which are disposed the cutting roles in a special succesion. After the presentation mechanism for the dislocating the rock calculate be the parameters of the working regim. The torsion moment establish and the pressing force at the cutting head i tis achieved as a of dimension stamp the cutting role on the working surface.

Calculation method of the working regim parameters at the drilling units for horizontal galleries in hard rocks

Dat fiind cazul unui inel articulat supus compresiunii pe directie diametrala, se remarca intuitiv dependenta magnitudinii deformatiilor de schema de incarcare utilizata; scopul articolului de fata este de a prezenta algoritmul clasic de calcul pentru estimarea starii de efort si deformatie ca functie de schema de incarcare, in scopul minimizarii deformatiilor obtinute. Rezultatele obtinute sunt comparate cu marimile finale oferite de metode numerice alternative.
Suppose you have a hinged ring in your hand; you compress it along a diameter and notice that the flexibility of the ring varies depending on the particular diameter along wich the compression is produced. The present paper is focused on elementary strenght of materials calculus concerning flexibility versus loading scheme optimisation.

Stress and deflection state evaluation study concerning the flexibility versus loading scheme optimization for a hinged ring case

Este propusa si argumentata utilizarea unui nou tip de amortizor in cazul sistemelor rotor flexibile. Amortizorul contine un fluid electrovascos care se solidifica atunci cand este parcurs de un curent electric si asigura astfel o amortizare datorita frecarii de tip Coulomb. Cu toate acestea, posibilitatile de a restrange atingerea vitezelor ctitice si de a reduce instabilitatile rotorului raman inca neconfirmate.
The use of a new type of damper in case of flexible rotor systems was proposed and argued. The damper contains an electro-viscous fluid that solidifies and ensures a Coulomb type friction damping when crossed by an electric current. Although, the possibilities to restrain the critical speeds reaching up and to decrease the instabilities of the rotor are still remaining unconfirmed.

The use of an electro-viscous damper in case of flexible rotor systems