Brazing and soldering is a method of joining metals by applying a filler metal of low melting temperature between the metals to be joined. When the filler metal melts it slightly diffuses into the base metals thus holding the parts together.
Soldering is divided into two classifications: soft and hard. In soft soldering filler metals with low melting temperature are used, while in hard soldering the melting temperature of filler metals is comparatively high.
In recent years, many complex forgings and stampings have been re-designed to allow fabrication by brazing or soldering of parts produced by mass-production techniques1. Such new designs have often resulted in striking reductions in cost2. In other instances, brazing and soldering have permitted the construction of assemblies too costly or complex to be produced by other techniques. Induction heating has proved to have been a valuable aid in these joining processes for many reasons. Among these are rapid heating and precise heat control. The former offers the possibility of localized heating for joining high-strength components with minimum loss of strength. The latter permits sequential brazing or soldering operations to have been performed effectively. Rapid heating also minimizes discolouration and thus facilitates cleaning.
Uniform joints with smooth fillets, obtained by induction soldering and brazing, decrease alloy consumption and produce parts which are identical in appearance3. Frequently, induction brazing and soldering permit a reduction in the required number of holding fixtures. At the same time, the resultant minimum of the fixtures increases their life and maintains their accuracy in alignment of the components to be joined. Basically, brazing and soldering involve fusion of a joining alloy between the surfaces of metal parts to be joined. If the metal surfaces are clean, intimate contact4 is established and the joining material alloys with each surface, forming a joint upon solidification during cooling. The two methods of joining differ primarily in the type and melting temperature of the alloy used to form the joint. In soldering, low-melting-temperature alloys, generally containing lead and tin, permit joints of limited strength to be made at temperatures below 800°F. Soldering with these alloys is often termed "soft soldering" and is used in fabricating radio condenser cans5, radiators, terminal strips, instrument cases, etc., and with the metals to be joined consisting of copper and copper alloys such as brass and bronze, carbon and alloy steels, nickel alloys and clad or plated aluminium. Thorough cleaning prior to and during heating is basic for successful soldered joints.
Many joint failures may have been traced directly to poor cleaning and inadequate fluxing. Surfaces to be joined should have been chemically cleaned (freed of heat treatment scale, corrosion products, grease, embedded graphite, etc.) prior to heating, and the joint areas fluxed as soon as possible to avoid contamination from handling or exposure. Suitable fluxes prevent oxidation of the joining alloy and metal surfaces to be joined and also dissolve any residual oxides during heating. They improve the wetting characteristics6 of the joining alloy, thus promoting its free flow upon melting. Zinc chloride and ammonium chloride fluxes in paste form are most frequently used in induction soldering, since they are the most active. Unfortunately, these fluxes leave residues which are corrosive, electrically conductive and hygroscopic. Such flux residues must be thoroughly removed. When this is impossible, as in soldering fine electrical assembly units, rosin or activated rosin-type fluxes which leave non-corrosive and electrically non-conductive residues are used. Fluxes for induction soldering are usually used in paste or liquid form.
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1. mass-productiontechniques - технические методы серийного производства
2. to result in striking reductions in cost - вызыватьрезкоеснижениестоимости
3. identical in appearance - одинаковыеповнешнемувиду
4. intimate contact — прочныйконтакт
5. radio condenser can - корпусрадиоконденсатора
6. wetting characteristics - характеристикисмачивания
VOCABULARY
braze паятьтвердымприпоем;
brazing пайкатвердымприпоем;
inductionb. пайка индуктированным током;
sequentialb. последовательная пайка;
solder припой; паять;
soldering пайка;
hards. пайка твердым сплавом;
softs. пайка мягким сплавом;
filler наплавочный материал;
diffuse распространяться, распылять;
stamping штамповка;
assembly агрегат, узел, сборка;
strength сила; прочность;
tensiles. сопротивление на разрыв, прочность на разрыв;
ultimates. предел прочности;
alloy сплавлять, легировать (сталь); сплав; сплавляемый;
fixture зажимное приспособление;
align выпрямлять, центрировать, выверять;
alignment центровка; совпадение осей;
joint соединение, стык;
lead свинец
tin олово;
strip планка;
terminals. полоска с контактами;
clad покрытый;
plate пластинка, плита; покрывать;
indexp. индексная пластинка, делительный диск;
mounting p. монтажнаяплита;
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platen стол (станка);
plating гальваническое покрытие;
failure повреждение;
feature конструктивная особенность;
flux флюс, поток, течение;
fluxing разжижение, офлюсование;
scale шкала; масштаб; окалина;
exposure выдержка;
rosin канифоль, смола;
residue остаток;
resistance сопротивление;
corrosionr. устойчивость против коррозии;
THREADS
Threads are applied for interconnection of machine parts and for transmitting motion from one part to another. When a thread is cut on the outside of a part it is known as an "external" or "male thread". A thread is called an "internal "or "female thread" when cut inside a part. Depending on the shape of the threading tool different profiles of thread are obtained, such as triangular, square or trapezoidal,
In practice triangular threads are most widely used. The main elements of a thread are: the angle of the thread, the major, minor and pitch diameters, the depth and the pitch.
The angle of a thread is the angle included between the sides of the thread and measured in an axial plane. The major, or outside, diameter of a thread d0, (sometimes referred to as "full diameter") is the distance between the two extreme outside points of the thread in the direction square to the axis1.
The major diameter is the largest diameter of the thread of a screw or a nut.
The minor diameter db being the smallest diameter of the thread, is the distance between the two extreme inside points of the thread measured at the right angle to the axis. The minor diameter is also called the "core diameter" or "root diameter".
The pitch diameter d2 is the distance between the two opposite parallel sides of the thread profile perpendicular to the thread axis. The depth t2 of the thread is the distance between the crest and the base of the thread measured normal to the axis, or
t2=(d0-d1)/2.
A crest is the top surface joining the two sides of a thread, while a base of a thread is the bottom surface joining the two adjacent threads. The pitch of a thread is the distance from a point of thread to the corresponding point of the next thread measured parallel to the axis.
Screw threads are of both right-hand and left-hand types. In right-hand threads the direction of the thread is from the right to the left. Right-hand threaded screws are turned clockwise to be screwed into a nut, while left-handed screws should be turned counterclockwise to do that.
In screw fastenings threads are made of various shapes, but always of the triangular type, such as: single thread, double thread and triple thread (Fig. 35). On the type of the latter depends the lead of the thread which is the distance a screw thread advances axially in one turn. On a single thread screw the lead and the pitch are the same; on the double thread screw the lead is twice the pitch, while on a triple thread screw the lead is three times the pitch.
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The most widely used systems of triangular threads in machine-building are: metric, inch and pipe threads. Each thread has its own angle and application. A metric thread profile resembles a triangle with an angle of 60° at its apex. Such a thread is widely used for bolts and nuts. An inch tread profile has an angle of 55°. This type of thread may be used when making spare parts for foreign-made machines. An angle of 55° is also used with pipe threads. Pipe threads are applied for gas and water pipes, as well as for clutches connecting such pipes.
1. in the direction square to the axis - внаправлении, перпендикулярномкоси
VOCABULARY
thread винтовая резьба, нарезка; нарезать резьбу;
acmet. трапецеидальная резьба;
buttresst. упорная резьба;
doublet. двухзаходная резьба;
externalt. наружная резьба;
femalet. внутренняя резьба;
flatt. прямоугольная резьба с малой высотой профиля;
incht. дюймовая резьба;
internalt. внутренняя резьба;
left-hand(ed) t. левая резьба;
malet. наружная резьба;
metrict. метрическая резьба;
pipet. трубная резьба;
right-hand(ed) t. праваярезьба;
roundt. круглая резьба;
screwt. резьба, винтовая резьба;
single (-start) t. однозаходная резьба;
squaret. квадратная резьба;
trapezoidalt. трапецеидальная резьба;
triangulart. треугольная резьба;
triplet. трехзаходная резьбу
Vee-t. треугольная резьба;
angle угол;
acute а. острый угол;
clearanceа. заднийугол;
crankа. угол поворота кривошипа;
cutting а. угол резания;
liр а. угол заострения;
obtuse а. тупой угол;
right а. прямой угол;
diameter диаметр;
cored. внутренний диаметр;
majord. наружный диаметр;
minord. внутренний диаметр;
pitchd. средний диаметр, диаметр делительной окружности;
rootd. внутренний диаметр;
crest вершина;
GEARS
A gear is a toothed wheel used to transmit rotary motion from one shaft to another. If power is transmitted between the two shafts, the angular velocity ratio of these two shafts is constant and the driving shaft and the driven shaft rotate at a uniform rate. Shafts may be parallel, intersecting, and non-coplanar. Types of gears may be diverse depending upon the above positions of the shafts. Gears may be classified according to their shape and according to the position which the teeth occupy respectively to the axis of rotation. The teeth cut on the face of л gear may be curved, straight or helical.
The main types of gears are: bevel gears, eccentric gears, helical or spiral gears, herringbone gears, screw gears, spur gears and worm gears.
Bevel gearing is used to transmit power between two shafts, which liein a common plane and whose axes intersect each other. The axes may be inclined to each other at any angle, although 90' is the most common one. The teeth of bevel gears may be either straight or spiral. In the straight bevel gears the elements of teeth converge to a common point called the "apex".
Eccentric gears operating on parallel shafts are used to transmit a varying angular velocity either continuously or for a portion of revolution.
Helical or spiral gears operate on parallel shafts at high speeds, providing maximum strength of gear teeth for a given width of face. Such gears are heat-treated and then ground to accurate shape and size, necessary for smooth and quiet running at high speeds. The teeth of helical gears, having been cut on a conical surface, curve continually toward or away from the apex of the cone upon which they are cut. These gears closely resemble bevel gears and are frequently called spiral bevel gears.
Similarly to helical gears, herringbone gears also operate on parallel shafts. Herringbone gears have helical teeth radiating from the center of the face towards the sides of the gear body. They are used where high speeds and high gear ratios are necessary.
Screw gearing is used for converting some rotary motion into a forward motion, and for connecting shafts which are not intersecting. Spur gears are gears having straight or helical teeth cut on a cylindrical surface at an angle to the shaft axis.
Spur gearing is used to transmit power between two shafts, the axes of which are parallel. Spur gearing may be divided into three types such as: external gearing, internal gearing and rack-and-pinion gearing. Rack-and-pinion gearing serves for converting rotary motion into forward motion and is widely used in lathes. It consists of a rack-and-pinion.
A worm gear is a gear having the teeth cut at an angle to the axis of rotation of the gear body and radially in the gear face. A worm gear is driven by a worm which resembles a large screw. Worm gearing is applied for transmitting power between non-intersecting shafts which are at right angles to each other.
In practice friction gearing and toothed gearing are most widely used for transmitting power from one shaft to another and for connecting the shafts. Friction gears are used for light and medium powers in machinery which is frequently started and stopped. Their advantages are flexibility and noiselessness. The disadvantages of friction gears are the thrust on the bearings and slippage. Toothed gears are used when a constant speed is desirable and the distance between the shafts is rather small. Transmission of rotary motion is performed by means of shafts and gears or gear trains mounted on them with the help of inserted keys.
Shafts may be of different length and diameters. When rotating, the shafts transmit both the rotation and the torque. Gears replace belt-and-pulley drives where positive motion is required. Gear teeth for all types mentioned above are made in mass production by the generating process on specially designed machines. In this process, the cutter used for cutting teeth has the form of a tooth of the mating gear. One of the most important gear-cutting processes is that of hobbing. In this process, the cutter used for hobbing gear teeth is made like a worm with gashes parallel to the axis to provide cutting edges on the worm. Such a cutter is called the "hob".
VOCABULARY
gear шестерня, зубчатое колесо; сцепляться;
bevelg. коническая передача, коническое зубчатое колесо;
chaing. цепная передача, цепное колесо, звездочка;
changeg. сменная шестерня;
eccentricg. эксцентрическая зубчатая передача, механизм
эксцентрика;
helicalg. геликоидальное (винтовое) колесо; косозубое колесо;
herringboneg. шевронное зубчатое колесо;
hypoidg. гипоидное зубчатое колесо;
maing. главная передача;
pick-offg. сменная шестерня;
screwg. винтовое зубчатое колесо;
segmentg. зубчатый сегмент; колесо с неполным зубчатым
венцом;
slidingg. передвижное зубчатое колесо, скользящее вдоль вала
зубчатое колесо;
spurg. цилиндрическое прямозубое колесо;
tumblerg. накидная шестерня;
wormg. червячное колесо;
gearbox коробка скоростей;
changeg. коробка перемены скоростей;
feed g. коробкаподач;
knee with feed g. консоль с коробкой подач;
sliderestfeedg. коробка подач бокового суппорта;
toolheadfeedg. коробка подач суппорта;
gearing зубчатая передача, зубчатое зацепление;
bevelg. коническое зубчатое зацепление;
externalg. внешнее зацепление, передача зубчатыми колесами
с внешним зацеплением;
frictiong. фрикционная передача;
internalg. внутреннее зацепление;
rack-and-piniong. передача шестерней и зубчатой рейкой;
screwg. винтовая передача;
spurg. цилиндрическая передача;
toothedg. зубчатая передача;
wormg. червячная передача;
velocity скорость;
angularv. угловая скорость;
shaft вал;
drives. ведущий вал;
drivens. ведомый вал;
drivings. ведущий вал;
feeds. ходовой валик, валик подачи;
hollows. пустотелый (полый) вал;
intermediates. промежуточный или передаточный вал;
intersectings. пересекающий вал;
splines. шлицевой вал;
coplanar копланарный, находящийся в одной плоскости;
plane плоский; плоскость;
apex вершина, пик;
face лицевая сторона; вид спереди; грань; наружная поверх
ность; грань резца; венец шестерни;
facing обработка торца, обточка торца;
converge сходиться;
grinding шлифование;
dryg. шлифовка всухую;
off-handg. ручное шлифование;
wetg. мокрое шлифование, шлифование с охлаждением;
rack зубчатая рейка;
rack-and-pinion реечная передача, кремальера;
flexibility гибкость;
thrust давление;
bearing подшипник, вкладыш (подшипника), опора, опорная по
верхность;
train зубчатая передача;
transmissiont. система зубчатых передач;
key шпонка; закреплять шпонкой; заклинивать;
adjustingk. установочный клин;
chuckk. торцовый ключ патрона;
insertedk. закладная шпонка;
torque крутящий момент, вращающий момент;
drive привод, передача; двигать; приводить во вращение;
beltd. ременная передача;
chaind. цепная передача;
cuttingd. привод резания;
feedd. привод подачи;
pulleyd. передача при помощи шкива;
driving передача, привод;
generate изготовлять (обрабатывать) зубчатые колеса способом
обкатки;
cutter фреза;
mating сопряженный с другой деталью, парный;
hob червячная фреза;
hobbing нарезание зубчатых колес (червячных) при помощи
червячной фрезы;
gash паз, канавка, надрез;
edge острие, лезвие; ребро; грань, край, кромка;
cuttingе. режущаякромка;
effective cutting е. рабочая режущая кромка;