Read and learn the following words and expressions:

coherent light source frequency ruby approximately inch smoothness considerable volatilized to reflect adjacent similar quality

- когерентное излучение - источник - частота - резиновый - приблизительно - дюйм - гладкость, плавность - значительный - улетученный - отражать - смежный, соседний - подобный - качество

1. Answer the following questions:

1. How can you characterize Laser beam welding?

2. What can you say about a laser beam production?

3. What can the laser be compared to?

4. Can the laser operate at short distance from the work piece?

5. What was one of the original questions concerning the use of the laser?

6. What do you know about the welding characteristics of the laser and of the electron beam?

7. Where are heating and cooling rates much higher in laser beam welding or in arc welding?

8. What kind of problems can rapid cooling rates create?

9. Where has the laser beam been used?

2. Fill in prepositions if necessary.

1. The focused laser beam has the highest energy concentration _______any known source_______energy.

2. The end surfaces of the ruby rod were ground flat and parallel and were polished______extreme smoothness.

3. The laser can be compared_______solar light beam for welding.

4. The laser can be used_______air.

5. The laser can operate_______considerable distance_______ the work piece.

6. The beam penetrates_______the metal vapor and melts the metal below.

7. It was found that once the metal is raised_______its melting temperature the surface conditions have little or no effect.

8. The power density_______the electron beam is only slightly greater.

9. Heating and cooling rates are much higher_______laser beam welding than in arc welding.

10. Rapid cooling rates can create problems such as cracking_______high carbon steels.

3. Give the summary of the text.

4. What parts of speech do the following words belong to? Translate these words into Russian.

Process, application, surface, focus, highest, project, early, crystal, extreme, vapor, melt, below, original, density, create, same.

5. Translate the following words paying attention to their suffixes.

Concentration, concentrated, producing, production, smoothness, considerable, consideration, differential, difference, different.

6. Translate the following groups of words.

Quality parameters, quality criteria, quality deviations, quality control system, required welding energy, constant quality, solar light beam, melting temperature, carbon steels, stainless steel.

Read and translate the text.

Text B

Improved Quality Through Ultrasonic Metal Welding

Height-volume production requires the strict adherence to predetermined quality parameters. This implies not only exact machine operation based on preset data, but also a simultaneous quality check of the weld against previously determined quality criteria. Ultrasonic metal welding offers the best prerequisites for optimum quality control as there are only a few specific process parameters which are easily measurable and thus controllable. Quality deviations are identified and usually offset during the welding process, i.e. they are adjusted.

Reasons for quality variations

Quality deviations may occur, for example, when workpieces have different dimensions, when the material quality (batches) differs and when contamination is excessive. A wrong insertion of the workpiece by the operator can also be identified by a quality control system.

Quality influences and quality parameters

The first task is to monitor the set machine data whereby welding pressure and amplitude are proportional in size to the supplied generator power output. Multiplying the power output with the welding time gives the required welding energy.

Welding in the energy mode

Welding in energy mode, i.e. with a constant energy setting, is known from ultrasonic plastics welding and can also be used for ultrasonic metal welding. To achieve a constant quality the welding time is automatically adjusted. Although this type of quality control is good with ultrasonic plastics welding, the approach has to be more carefully applied when it comes to ultrasonic metal welding.

Control of welding energy is not always sufficient Contact-free probe to determine the degree of compression

Considering that were applications which require only minimum welding energy, the total of all system-caused losses amounts to some 80% of the total necessary welding energy (leaving 20% effective welding energy), it becomes evident that small modifications in the workpieces to be welded require only a minor adjustment to the welding energy. The control of the welding energy in respect of welding time does not take into account possible insufficiencies and variations of the machine components.

The tolerances are even higher when the workpieces to be welded are of different quality and have different service conditions.

All these varying influences can have a considerable effect on the welding quality.

Mechanical compression as a quality parameter

As the parts to be welded may deform during the welding process, the mechanical compression of the parts after they have been welded together may constitute an important quality measure. Contact-free measuring devices in the welding equipment determined the degree of compression by measuring the movement (stroke) of the welding tools during the process. The starting point of this stroke is the position of the sonotrode under pressure before the ultrasonic is triggered.