Hole 20 is drilled on the machine. Drilling holes in metal: methods, tools, useful tips

1) A grinding stone with a radius of 30 cm makes one revolution in 0.6 s. Where are the points with the highest linear speed located, and what is it equal to?
2) Find the centripetal acceleration acting on the teeth of a circular saw with a diameter of 600 mm at a speed of 3000 rpm?
3)

human work, if he applied a force of 240H to the rope, what power did the person develop in this case?

up to a speed of 20 m / s. What is the modulus of the force that accelerated the car?

3) At a speed of 54 km / h, the traction force of the car engine is 800N. What is the engine power?

1) to the same place where the movement is directed; 2) against the direction of movement; 4) regardless of the direction of movement;
2. A physical quantity equal to the ratio of the movement of a material point to a physically small period of time during which this movement occurred is called
1) the average speed of the non-uniform movement of a material point; 2) instantaneous velocity of a material point; 3) the speed of uniform movement of a material point.
3. In which case is the acceleration module larger?
1) the body moves at a high constant speed; 2) the body quickly picks up or loses speed; 3) the body is slowly gaining or losing speed.
4. Newton's third law describes:
1) the action of one body on another; 2) the action of one material point on another; 3) interaction of two material points.
5. The locomotive is coupled to the wagon. The force with which the locomotive acts on the car is equal to the forces that impede the movement of the car. Other forces do not affect the movement of the car. Consider the reference system connected with the Earth to be inertial. In this case:
1) the car can only rest; 2) the car can only move at a constant speed; 3) the car is moving at a constant speed or is at rest; 4) the car is moving with acceleration.
6. An apple of mass 0.3 kg falls from a tree. Choose the correct statement
1) the apple acts on the Earth with a force of 3N, and the Earth does not act on the apple; 2) The earth acts on the apple with a force of 3N, but the apple does not act on the earth; 3) the apple and the Earth do not act on each other; 4) the apple and the Earth act on each other with a force of 3 N.
7. Under the action of a force of 8N, the body moves with an acceleration of 4m/s2. What is its mass?
1) 32 kg; 2) 0.5kg; 3) 2 kg; 4) 20kg.
8. With dry friction, the maximum static friction force:
1) more sliding friction force; 2) less force of sliding friction; 3) is equal to the force of sliding friction.
9. The force of elasticity is directed:
1) against displacement of particles during deformation; 2) in the direction of displacement of particles during deformation; 3) nothing can be said about its direction.
10. How do the mass and weight of a body change when it moves from the equator to the pole of the Earth?
1) the mass and weight of the body do not change; 2) body weight does not change, weight increases; 3) body weight does not change, weight decreases; 4) body weight and weight decrease.
11. After turning off the rocket engines, the spacecraft moves vertically upward, reaches the top of the trajectory, and then moves downward. On what part of the trajectory in the ship is the state of weightlessness observed? Air resistance is negligible.
1) only during the upward movement; 2) only during downward movement; 3) only at the moment of reaching the top point of the trajectory; 4) during the entire flight with idle engines.
12. An astronaut on Earth is attracted to it with a force of 700N. With what approximate force will it be attracted to Mars, being on its surface, if the radius of Mars is 2 times, and the mass is 10 times less than that of the Earth?
1) 70N; 2) 140 N; 3) 210 N; 4) 280N.
Part 2
A body is thrown at an angle to the horizon with an initial velocity of 10 m/s. What is the speed of the body at the moment when it was at a height of 3 m?
Determine the force of gravity acting on a body of mass 12 kg, raised above the Earth at a distance equal to one third of the earth's radius.
What work must be done to lift a load of 30 kg to a height of 10 m with an acceleration of 0.5 m/s2

Holes are drilled and countersinked on radial drilling machines. The rotary console of the machine with a length of up to 4.5 m allows you to drill holes on sheets or profiles without moving them to guide the drill to the marked hole centers. Holes are drilled using cores that mark the centers of the holes. Identical parts from sheet material are drilled in a package up to 80 mm thick.

The main drilling time is calculated by the formula:

where l- drilling depth, mm; l 1 - the size of the plunge and overrun of the drill, depending on the type of drill and diameter, mm (with a drill diameter of 10 mm, this size is 5 mm; up to 20 mm - 8 mm; up to 30 mm - 12 mm); s c - drill feed per revolution, mm; n- spindle speed, rpm,

where υ - cutting speed, m/min.

The spindle speed and drill feed are determined according to the tables of cutting conditions, depending on the brand of material, diameter and type of drill, and taking into account the passport data of the machine. Auxiliary time includes the time spent on laying and fixing the sheet, details; on the supply of the support to the center of the hole, the removal of the drill from the hole and cleaning it from chips; to turn the feed on and off and remove the part sheet. Auxiliary time is divided into the time given for one hole and for one part, set according to chronometric observations. Examples of auxiliary time values ​​for drilling holes on parts weighing over 50 kg are given in Table. 30, 31.

Workplace maintenance time includes time for adjusting and lubricating the machine, changing tools, operating the machine, and cleaning the workspace. The maintenance time of the workplace, according to the photographs of the working day, is 4% of the operational time.

The time for rest and personal needs is taken equal to 4% for manual filing, and 2% for automatic filing.

The preparatory and final time includes the costs of obtaining the task and getting acquainted with it, obtaining tools, fixtures, instructing the master, and handing over the work performed. The preparatory and final time, according to the photographs of the working day, does not exceed 4% of the operational time.

Coefficient TO, taking into account the time for servicing the workplace, time for rest and personal needs, and preparatory and final time, when working with manual feed, it is 1.12, and with automatic feed, it is 1.10.

Piece-calculation time for drilling holes is calculated by the formula

where T 0 - the main time of drilling one hole, min; t в1 - auxiliary time for one hole, min; t vd - auxiliary time for the part, min; m- the number of holes on the part. Examples of the values ​​​​of the piece-calculation time for drilling holes are given in table. 32.

The norm of time for drilling holes in sheets, parts included in the tasks being performed is calculated by the formula (22), in which ΣТ shk is the sum of the piece-calculation time for drilling holes on sheets, parts included in the task; N- the number of sheets, details.

Example. Calculate the rate of time for drilling holes on the radial drilling machine with automatic feed with high-speed steel drills: in four sheets 16 mm thick - 140 holes with a diameter of 12 mm on each sheet; in eight strips 10 mm thick - 125 holes with a diameter of 20 mm on each strip.

Solution. The norm of time is calculated by the formula (22). The piece-calculation time for drilling holes is determined from Table. 32 for sheets with a thickness of 16 mm, with a hole diameter of 12 mm and automatic feeding T shk = 40 min for 100 holes, and for 140 holes T shk 1 = 40-1.4 = 56 min; for strips 10 mm thick with a hole diameter of 20 mm and automatic feeding T shk = 45 min for 100 holes, and for 125 holes T shk 2 = 45-1.25 = 56.25 min. Norm of time for the task: T n \u003d 56-4 + 56.25-8 \u003d 674 min.

Bending of sheet and profile steel. Currently, in shipbuilding, mainly cold bending is used on roll bending machines (rollers), hydraulic presses, sheet bending machines, flange bending machines and on profiling and bending presses, etc.

The main time of bending work - the time of sheet rolling on the machine until the required shape is obtained - is found by the formula:

where L is the path traveled by the sheet in one pass; υ - the speed of the passage of the sheet at idle, m/min; υ =πDn/1000; D - diameter of the leading roll of the bending machine, mm; n - frequency of rotation of the driving roll, rpm; determined according to the passport data of the equipment; TO c - correction factor that takes into account the decrease in speed depending on the thickness of the rolled sheet: with a sheet thickness of 3-6 mm TO c = 0.90; 8-10 mm - 0.80; 12-16 mm - 0.75; i- the number of passes (rolling of the sheet), which must be done to obtain a given perish;

Here B is the width of the section of the sheet undergoing bending, mm; b- distance between rolling tracks (step), mm; K m is a correction factor that takes into account the effect of material thickness on bending time:

Auxiliary time consists of the time spent on marking the control lines and boundaries of the sheet rolling, feeding the sheet with a crane and laying it on the drive roll, changing the direction of rotation of the roll, turning the sheet during bending; machine control; sheet removal; pattern check. Auxiliary time values, according to the timing observations given in Table 33.

The maintenance time of the workplace consists of the cost of checking and adjusting the operation of all mechanisms of the machine, lubricating it during operation and cleaning the workplace. According to the photographs of the working day, it is equal to 3% of the operational time.

Time for rest and personal needs when working on bending machines is 7 % operating time.

The preparatory and final time includes the time for receiving the task and getting acquainted with it, obtaining the tool and templates, initial setting of the machine in accordance with the nature of the death, instructing the master and handing over the work performed. According to the photo of the working day, the preparatory and final time does not exceed 5 % operational.

Piece-calculation time for bending one workpiece is determined by the formula T shk = (T 0 + T B)K, where T 0 - main bending time, min; T in - auxiliary time for one part, min. Coefficient TO to the calculation of piece-calculation time is 1.15 . Examples of the values ​​of the piece-calculation time for bending sheets and profile steel are given in table. 34, 35.

The norm of time for bending sheet and profile material is found by the formula (22), in which ΣТ shk is the sum of piece-calculation time for bending all sheets and profiles for a given task; N- the number of parts (sheets, profiles).

The time in the tables is calculated for bending parts made of steel grades 10KhSND, 10G2S1D in three-roll rolls with a roll speed of 6-8 m/min, with the number of parts in a batch of 3 pcs. and a bending angle of 90°. Under other conditions, coefficients are applied to the time standards: with the number of parts in a batch of 1 piece - K n - U; 5 pieces - 0.95; 10 pieces - 0.90; for parts made of materials grade AMg, 09G2 K m = 0.90; AK-16 - 1.3; KD - 1.5; at a bending angle of 45 ° K g - 1.40; 60° - 1.15; 80° - 1.05; 100° -0.95; 120°-0.85; 140° -0.75; 150 ° -0.70, at a speed of rotation of the rolls up to 6 m / min K in -1.20; over 8 m/min - 0.8; for bending workpieces with a width of less than 500 mm K 3 - 0.80; when bending in four-roll rolls K k - 0.85; with the value of the arrow of sheet death 40 mm K s - 0.80; 80 mm - 0.90; 120 mm - 1.00; 160mm-1.15; 200 mm - 1.25; 300 mm -1.45; 500 mm - 1.80; with the value of the arrow of death of parts from shaped and long products of 100 mm K s - 0.80; 200 mm -1.00; 300mm-1.20; 500 mm - 1.40.

Example. Calculate the norm of time for bending parts from sheet metal grade 09G2 on three-roll sheet-bending rolls with a rotation speed of 6 m/min. Cylindrical parts with a bending angle of 60° from blanks 2000 mm long, 1000 mm wide and 12 mm thick, number of parts 5 pcs. Calculate the bending time for hydraulic press parts from a welded T-section with variable curvature from KD steel with a sag of 300 mm from blanks 3000 mm long and a profile wall height of 200 mm, the number of parts is 10 pcs., bending - per shelf.

Solution. The norm of time is calculated by the formula (22). We determine piece-calculation time. The time for bending cylindrical parts from sheet metal on sheet-bending rolls (see Table 34) with a workpiece length of 2000 mm, a width of 1000 mm and a thickness of 12 mm T sh = 0.41 h, and taking into account the above coefficients for bending parts from the material 09G2 K m = 0.90; K g \u003d 1.15 for a bend angle of 60 °, K n \u003d 0.95 for the number of parts in a batch - 5 pcs. T shk1 \u003d 0.41 -0.90 × 1.15-0.95 \u003d 0.403 h. The time for bending parts from a welding T-profile with variable curvature on a hydraulic press is determined from Table 35 with a workpiece length of 3000 mm and a profile wall height of 200 mm; T shk = = 0.98 h, and taking into account the coefficient for bending parts made of steel KD K m = 1.5; K c \u003d 1.20 by the size of the arrow of death 300 mm; K n \u003d 0.90 for the number of parts in a batch of 10 pcs. T shk2 \u003d \u003d 0.98-1.5-1.2-0.9 \u003d 1.587 h.

The norm of time for the task T n \u003d 0.403-5 + 1.587-10 \u003d 17.88 hours.

The work of drilling holes in metal, depending on the type of holes and the properties of the metal, can be performed with different tools and using different techniques. We want to tell you about drilling methods, tools, as well as safety precautions when performing these works.

Drilling holes in metal may be needed during repairs engineering systems, household appliances, car, creating structures from sheet and profile steel, designing crafts from aluminum and copper, in the manufacture of circuit boards for radio equipment, and in many other cases. It is important to understand what kind of tool is needed for each type of work so that the holes are the right diameter and in a strictly intended place, and what safety measures will help to avoid injury.

Tools, fixtures, drills

The main tools for drilling are manual and electric drills, and, if possible, drilling machines. The working body of these mechanisms - the drill - can have a different shape.

There are drills:

• spiral (most common);
• screw;
• crowns;
• conical;
• feathers, etc.

Drill production various designs standardized by numerous GOSTs. Drills up to Ø 2 mm are not marked, up to Ø 3 mm - the section and steel grade are indicated on the shank, larger diameters may contain additional information. To obtain a hole of a certain diameter, you need to take a drill a few tenths of a millimeter smaller. The better the drill is sharpened, the smaller the difference between these diameters.

Drills differ not only in diameter, but also in length - short, elongated and long are produced. Important information is the ultimate hardness of the metal being processed. The shank of the drills can be cylindrical and conical, which should be borne in mind when selecting a drill chuck or adapter sleeve.

1. Drill with a cylindrical shank. 2. Tapered shank drill. 3. Drill with a sword for carving. 4. Center drill. 5. Drill with two diameters. 6. Center drill. 7. Conical drill. 8. Conical multi-stage drill

For some work and materials, special sharpening is required. The harder the metal being processed, the sharper the edge must be sharpened. For thin sheet metal, a conventional twist drill may not be suitable, you will need a tool with a special sharpening. Detailed recommendations for various types drills and processed metals (thickness, hardness, hole type) are quite extensive, and in this article we will not consider them.

Various types of drill sharpening. 1. For hard steel. 2. For stainless steel. 3. For copper and copper alloys. 4. For aluminum and aluminum alloys. 5. For cast iron. 6. Bakelite

1. Standard sharpening. 2. Free sharpening. 3. Diluted sharpening. 4. Heavy sharpening. 5. Separate sharpening

To fix parts before drilling, a vice, stops, conductors, corners, clamps with bolts and other devices are used. This is not only a safety requirement, it is actually more convenient, and the holes are of better quality.

To chamfer and process the surface of the channel, they use a countersink of a cylindrical or conical shape, and to mark a point for drilling and so that the drill does not “jump off” - a hammer and a center punch.

Advice! The best drills are still considered to be those produced in the USSR - exact adherence to GOST in geometry and metal composition. German Ruko with titanium coating are also good, as well as drills from Bosch - proven quality. Good feedback about Haisser products - powerful, usually with a large diameter. The Zubr drills, especially the Cobalt series, proved to be worthy.

Drilling modes

It is very important to correctly fix and guide the drill, as well as select the cutting mode.

When making holes in metal by drilling, important factors are the number of revolutions of the drill and the feed force applied to the drill, directed along its axis, providing the penetration of the drill at one revolution (mm / rev). When working with different metals and drills, different cutting conditions are recommended, and the harder the metal being processed and the larger the diameter of the drill, the lower the recommended cutting speed. Indicator correct mode— beautiful, long shavings.

Use the tables to choose the right mode and not dull the drill prematurely.

Table 2. Correction factors

Table 3. Revolutions and feed at different diameter drill and drilling carbon steel

Types of holes in metal and methods for drilling them

Types of holes:

• deaf;
• through;
• half (incomplete);
• deep;
• large diameter;
• for internal thread.

Threaded holes require the determination of diameters with tolerances established in GOST 16093-2004. For common hardware, the calculation is given in table 5.

Table 5. The ratio of metric and inch threads, as well as the selection of the hole size for drilling

through holes

Through holes penetrate the workpiece completely, forming a passage in it. A feature of the process is the protection of the surface of the workbench or tabletop from the exit of the drill beyond the workpiece, which can damage the drill itself, as well as provide the workpiece with a “burr” - a hart. To avoid this, use the following methods:

• use a workbench with a hole;
• put a gasket made of wood or a “sandwich” under the part - wood + metal + wood;
• put a metal bar under the part with a hole for the free passage of the drill;
• reduce the feed rate at the last stage.

The latter method is mandatory when drilling holes "in place" so as not to damage closely spaced surfaces or parts.

Holes in thin sheet metal are cut with spatula drills, because the twist drill will damage the edges of the workpiece.

blind holes

Such holes are made to a certain depth and do not penetrate the workpiece through and through. There are two ways to measure depth:

• limiting the length of the drill with a sleeve stop;
• limiting the length of the drill with an adjustable stop chuck;
• using a ruler fixed on the machine;
• a combination of methods.

Some machines are equipped with an automatic feed to a given depth, after which the mechanism stops. During the drilling process, it may be necessary to stop the work several times to remove the chips.

Holes of complex shape

Holes located on the edge of the workpiece (half) can be made by connecting two workpieces or a workpiece and a gasket with faces and clamping with a vise and drilling a full hole. The gasket must be made of the same material as the workpiece being processed, otherwise the drill will “leave” in the direction of least resistance.

A through hole in the corner (shaped rolled metal) is performed by fixing the workpiece in a vice and using a wooden gasket.

It is more difficult to drill a cylindrical workpiece tangentially. The process is divided into two operations: preparation of a platform perpendicular to the hole (milling, countersinking) and drilling itself. Drilling holes in angled surfaces also begins with site preparation, after which a wooden spacer is inserted between the planes, forming a triangle, and a hole is drilled through the corner.

Hollow parts are drilled, filling the cavity with a cork made of wood.

Stepped holes are produced using two techniques:

1. Reaming. The hole is drilled to the full depth with a drill of the smallest diameter, after which it is drilled to a given depth with drills with diameters from smaller to larger. The advantage of the method is a well-centered hole.
2. Reducing the diameter. A hole of maximum diameter is drilled to a given depth, then the drills are changed with a successive decrease in diameter and a hole deepening. With this method, it is easier to control the depth of each step.

1. Drilling a hole. 2. Diameter reduction

Large diameter holes, annular drilling

Obtaining holes of large diameter in massive workpieces, up to 5-6 mm thick, is a laborious and costly business. Relatively small diameters - up to 30 mm (maximum 40 mm) can be obtained using cone, and preferably step-cone drills. For holes with a larger diameter (up to 100 mm), hollow bi-metal hole saws or hole saws with carbide teeth with a center drill will be required. Moreover, the craftsmen traditionally recommend Bosch in this case, especially on hard metal, such as steel.

Such annular drilling is less energy-intensive, but may be more financially costly. In addition to drills, the power of the drill and the ability to work at the lowest speeds are important. Moreover, the thicker the metal, the more you want to make a hole on the machine, and with a large number of holes in a sheet with a thickness of more than 12 mm, it is better to immediately look for such an opportunity.

In a thin-sheet blank, a large-diameter hole is obtained using narrow-toothed crowns or a milling cutter mounted on a grinder, but the edges in the latter case leave much to be desired.

Deep holes, coolant

Sometimes a deep hole is required. In theory, this is a hole whose length is five times the diameter. In practice, deep drilling is called, requiring forced periodic removal of chips and the use of coolants (cutting fluids).

In drilling, coolants are needed primarily to reduce the temperature of the drill and workpiece, which are heated by friction. Therefore, when making holes in copper, which has a high thermal conductivity and is itself capable of removing heat, coolant can be omitted. Cast iron is drilled relatively easily and without lubrication (except for high-strength ones).

In production, industrial oils, synthetic emulsions, emulsols and some hydrocarbons are used as coolants. In home workshops you can use:

• technical vaseline, castor oil - for mild steels;
• laundry soap - for aluminum alloys of the D16T type;
• a mixture of kerosene with castor oil - for duralumin;
• soapy water - for aluminum;
• turpentine diluted with alcohol - for silumin.

The universal coolant can be prepared independently. To do this, you need to dissolve 200 g of soap in a bucket of water, add 5 tablespoons of machine oil, you can use it, and boil the solution until a soapy homogeneous emulsion is obtained. Some masters use lard to reduce friction.

Deep holes can be made by solid and annular drilling, and in the latter case, the central rod formed by the rotation of the crown is broken out not entirely, but in parts, weakening it with additional holes of small diameter.

Solid drilling is performed in a well-fixed workpiece with a twist drill, through the channels of which coolant is supplied. Periodically, without stopping the rotation of the drill, it is necessary to remove it and clean the cavity from chips. The work with a twist drill is carried out in stages: first, a short hole is taken and a hole is drilled, which is then deepened with a drill of the appropriate size. With a significant depth of the hole, it is advisable to use guide bushings.

With regular drilling deep holes we can recommend the purchase of a special machine with automatic coolant supply to the drill and precise centering.

Drilling by marking, template and jig

You can drill holes according to the markings made or without it - using a template or a jig.

Marking is done with a punch. A hammer blow marks a place for the tip of the drill. A felt-tip pen can also mark a place, but a hole is also needed so that the tip does not move from the intended point. The work is carried out in two stages: preliminary drilling, hole control, final drilling. If the drill "left" from the intended center, notches (grooves) are made with a narrow chisel that guide the tip to a given place.

To determine the center of a cylindrical workpiece, a square piece of tin is used, bent at 90 ° so that the height of one shoulder is approximately one radius. Applying a corner from different sides of the workpiece, draw a pencil along the edge. As a result, you have an area around the center. You can find the center by the theorem - the intersection of perpendiculars from two chords.

A template is needed when making a series of parts of the same type with several holes. It is convenient to use it for a pack of thin-sheet blanks connected with a clamp. This way you can get several drilled blanks at the same time. Instead of a template, a drawing or diagram is sometimes used, for example, in the manufacture of parts for radio equipment.

The conductor is used when the accuracy of maintaining the distances between the holes and the strict perpendicularity of the channel are very important. When drilling deep holes or when working with thin-walled tubes, in addition to the conductor, guides can be used to fix the position of the drill relative to the metal surface.

When working with a power tool, it is important to remember human safety and prevent premature wear of the tool and possible marriage. For this reason, we have collected some helpful tips:

1. Before work, you need to check the fastening of all elements.
2. Clothing when working on a machine or with an electric drill should not be with elements that can fall under the action of rotating parts. Protect your eyes from chips with goggles.
3. The drill, when approaching the surface of the metal, must already rotate, otherwise it will quickly become dull.
4. It is necessary to remove the drill from the hole without turning off the drill, reducing the speed if possible.
5. If the drill does not go deep into the metal, then its hardness is lower than that of the workpiece. Increased hardness in steel can be detected by running a file over the sample - the absence of traces indicates increased hardness. In this case, the drill must be selected from a carbide with additives and work at low speeds with a small feed.
6. If a small diameter drill does not fit well in the chuck, wind a few turns of brass wire around its shank, increasing the gripping diameter.
7. If the surface of the workpiece is polished, put a felt washer on the drill to ensure that it does not scratch even when it comes into contact with the drill chuck. When fastening workpieces made of polished or chrome-plated steel, use spacers made of fabric or leather.
8. When making deep holes, a rectangular piece of foam placed on a drill can serve as a measuring instrument and at the same time blow off small chips while rotating.

Job 4

Example 4 On a vertical drilling machine 2H135, a through hole with a diameter of d=20 mm is drilled to a diameter of D=50 H12 (+0.25) to a depth of l=70 mm. Processed material - Steel 45 with δ B = 680 MPa, workpiece - stamping. Cooling - emulsion. The processing sketch is given in Figure 14.

REQUIRED: Select cutting tool, the material of its cutting part, its design and geometric parameters. Assign a cutting mode according to the standards and determine the main processing time. Give a processing sketch. Figure 12 - Workpiece processing sketch

SOLUTION: Ι. We select a drill and set its design and geometric parameters. We accept a twist drill with a diameter of D = 50 mm; material of the cutting part - high-speed steel P18 (appendix 1, page 349). You can also accept steel that is not listed in Appendix 1.

Geometric elements: sharpening shape - double, (app. 2, p. 355). Due to the lack of recommendations in the standards for choosing the remaining geometric parameters, we accept them from the reference book: 2γ=118˚, 2γ 0 =70˚, ψ=40…60˚, with standard sharpening ψ=55˚; α=11˚, length of the secondary edge b=9 mm. (Table 45, p. 152), ω=24…32˚; for standard drills D>10 mm for processing structural steel ω=30˚.

Setting the cutting mode

1. Cutting depth:

t=D-d/2=50-20/2=15 mm.

2. Assign the serve (Map 52, p. 116). According to the second group of feeds, assuming that a workpiece of medium hardness is being drilled, we find for processing a steel workpiece D=50 mm and d=20 mm S 0 =0.6...0.8 mm/rev. We correct the feed on the machine S 0 \u003d 0.8 mm / rev.

We check the accepted feed by the axial force allowed by the strength of the feed mechanism of the machine. Due to the absence in the table standards of the value of the axial component of the cutting force during reaming, we determine its value from the reference book (p. 435):

P 0 \u003d C p ∙D Qp ∙t xp ∙S 0 yp ∙K p (19)

We write out from table 32, p.281 coefficients and exponents for formula (19) for drilling structural steel with δ in = 750 MPa; high-speed steel tool: C p =37.8; Qp=0; xp=1.3; yp=0.7.

We take into account the correction factor for the cutting force K p \u003d K mp (according to Table 9, p. 264):

Kmp = where np=0.75, Kmp =

P 0 \u003d 37.8 ∙ 50 0 ∙ 15 1.3 ∙ 0.8 0.7 ∙ 0.93 \u003d 1016 kgf \u003d 9967 N.

At the machine 2N135 R 0 max \u003d 1500 kgf, R 0< Р 0 max (1016<1500) Следовательно назначенная подача S 0 =0,8 мм/об вполне допустима.

3. We assign the period of durability of the drill according to the standard, Table 2, page 98. For a drill with a diameter of D=50 mm, a tool life of T=90 min is recommended. Permissible wear of the drill on the back surface h 3 \u003d 1 mm on the ribbon h 3 \u003d 1.5 mm.

4. We determine the speed of the main cutting movement, which is allowed by the cutting properties of the drill. According to map 53 (p. 117) we find for the form of sharpening DP, diameter differences D- d=50-20=30 mm. (according to the column “up to 50 mm”), S 0 up to 1 mm / rev, which V table \u003d 13.6 m / min. For given processing conditions given in map 53, the correction factor K nv =1. According to the note to map 53, it is necessary to additionally take into account the correction factor K mv on map 42, pages 104-105. For steel 45 with δ in = 680 MPa (see the range 560 ... 750 MPa) K mv = 1, therefore:

V=V table ∙1∙1=13.6∙1∙1=13.6 m/min.

5. Determine the spindle speed corresponding to the found speed of the main cutting movement:

We correct the speed according to the passport data of the machine and set the actual speed of the spindle n d \u003d 90 min -1.

6. Actual speed of the main cutting movement

7. We determine the power spent on cutting (map 54, p. 118 ... 119). For δ in \u003d 560 ... 680 MPa, D-d up to 32 mm, S 0 to 0.84 mm / rev, at V up to 15.1 m / min we find N table \u003d 3.3 kW. Correction factors for power in the indicated map are not given, therefore: N res = N tab = 3.3 kW.

8. We check whether the drive power of the machine is sufficient N cut< N шп. У станка 2Н135 N шп = N д ∙0,8=3,6кВт. Следовательно обработка возможна так как N рез < N шп.

9. Determine the main processing time.

When reaming with a drill with a single sharpening, the infeed is y=t∙ctgγ, and with a double sharpening y=t 1 ∙ctgγ 0 + t 2 ∙ctgγ, where t 1 is the depth of cut in the area of ​​the secondary edges; t 1 =in∙sinγ 0 ; the length of the secondary edge in = 9 mm, 2γ 0 =70º; 2γ=118º; t 1 \u003d 9 ∙ sin35º \u003d 9 0.57 \u003d 0.51; t 2 - depth of cut (mm) in the area of ​​the main cutting edges: t 2 \u003d t-t 1 \u003d 15-5.1 \u003d 9.9 mm. At 5.1∙ctg35º+9.9∙ctg59º=5.1∙1.43+9.9∙0.6=13.2 mm. Overrun in the area ∆=1…3 mm. We accept 3 mm. Then: L=70+13.2+3=86.2 mm.

Task 4. On a vertically drilling machine 2N135, a hole with a diameter d is drilled to a diameter D to a depth of 1 (Table 4).

REQUIRED: Select the cutting tool, the material of its cutting part, its design and geometrical parameters. Assign a cutting mode according to the normative data and determine the main processing time. Give a sketch of the processing of the part.

Table 4

Data for task 4

Table 4 continued

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