- •Unit 3 turning and turning machines (lathes)
- •1. Read and memorize the following words and word-combinations:
- •Types of lathes
- •1. Give the main points of the text, answering the following questions:
- •2. Choose synonyms out of the following list:
- •3. Fill in the blanks with the suitable words from the text. The words are given below.
- •4. Perform the following tasks, basing of the text.
- •5. Characterize lathes according to the following plan:
- •Text 2 Engine Lathe
- •1. Give the main points of the text, answering the following questions:
- •2. Using the text, give derivatives from the following words and translate them into Russian:
- •3. Replace Russian words and word combinations by the corresponding English equivalents:
- •4. Make up questions to which the italicized words are answers:
- •5. Make up a summary of the text. Text 3
- •Vertical Eight - Spindle Semiautomatics
- •5. Give a brief summary of the text.
- •1. Answer the following questions, using the information from the text:
- •2. Translate the following groups of words, paying attention to the meaning of suffixed:
- •3. Fill in the blanks with the preposition: for, of, in, with, by, out, from, to.
- •4. Find the English equivalents for the following:
- •5. Supply the missing word:
- •Upright Drill Presses
- •1. Underline the suffixes in the following words and state what part of speech they belong to:
- •3. Translate the following sentences observing different meanings of the italicized words and word combinations:
- •4. Guess the meaning:
- •5. Describe the function and characteristics of the principal units of an upright drill press, using the active vocabulary of the text:
- •6. Try to translate the text without using the dictionary:
- •Radial Drills
- •1. Find in the text:
- •2. Find English equivalents:
- •3. Make sentences out of the two parts:
- •4. Translate the following in writing.
- •5. Make a brief summary of the text.
- •Unit 5 grinding and grinding machines
- •Purpose and Field of Application of Grinding Machines
- •Text 2 Cylindrical Grinding Machines
- •6. Summarize the text. Text 3
- •Internal Grinding Machines
- •1. Name the main points of the text answering the following questions:
- •2. Fill in the blanks using the words below:
- •3. Find in the text English equivalents for the following words and word combinations:
- •4. Using the text supply
- •5. Summarize the text.
Radial Drills
Radial drills are intended for machining large heavy work with a great number of cutting tools in piece and lot productions. It differs from the upright drill press in that the spindle axis is made to coincide with the axis of the hole being machined by moving the spindle in a system of polar coordinates to the hole while the work is stationary. The arrangements of the principal units is such that the spindle with the tool can be easily moved to any point within the working zone by traversing drill head along the ways of arm and swivelling the arm about column.
Self-propelled radial drills, frequently employed in bridge building, have the drill mounted on a self-propelled truck which travels along railway tracks. They are rigidly clamped for operation at the required site by means of hydraulic clamping shoes which grasp the rails.
The primary cutting motion v in a radial drill is spindle rotation, while the feed motion is the axial feed of the spindle with the quill.
Auxiliary motions include swivelling of the arm and clamping it on the column, vertical traverse of the arm and it’s clamping at the required height on the column, traversing of the spindle head and its clamping along the arm, changing spindle speeds and feeds, etc.
The principal units of a radial drill are column, base, arm, arm elevating and clamping mechanism, and drill head.
The column consists of two parts: the stationary inner column, secured rigidly to the base, and the rotary outer column. The outer column is clamped in the required position by yoke which encircles the papered surfaces on the flanges of the two columns.
The base and traverse are grey iron casting stiffened by internal ribbing. The arm has horizontal ways along which the drill head travels.
The arm elevating and clamping mechanism provides for rapid vertical traverse of the arm along the outer column and rigid clamping in the required position. Clamping and unclamping of the arm are automatically interlocked with arm traverse along the column. From the motor power is transmitted through reducing gear to the vertical screw. Ball type safety clutch protects the motor and the mechanism against overloads.
The drill head of a radial drill is a self-contained unit combining the speed and feed gearboxes, feed mechanism, spindle, and head traverse and clamping mechanism.
The head is clamped rigidly in the required position on the arm by an eccentric mechanism located at the rear of the head housing.
Heads of heavy radials are equipped with speed and feed preselector controls. Speeds and feeds are changed by either electromechanical or hydraulic means.
The use of such mechanism substantially reduces handling time required in changing speeds and feeds. This circumstance is of special importance for radial drills since they usually perform operations requiring changes of cutting tools and consequent changes in speeds and feeds.
Further reduction of time losses connected with speed and feed changing can be by equipping the heads with mechanism for automatically changing speeds and feeds when going over from operation to operation.
The most promising current method for introducing automatically in feed and speed changing involves built-in electro-magnetic clutches in the drill head.
In a system of automatic control, speed and feed changing in a single-spindle head should be connected with the withdrawal of the spindle to the initial position.
EXERCISES