Typical technology for manufacturing shafts in single production.

A shaft is a machine part that transmits rotating forces. A shaft is a rotating body of cylindrical, conical or other shape, supported by two or more supports. Pulleys, gears, flanges, flywheels, etc. can be attached to the shaft.

Typical shaft manufacturing technology:

  • Cleaning;
  • Heat treatment;
  • Editing;
  • Procurement operation (cutting);
  • Centering;
  • Turning operation;
  • Milling operation;
  • Drilling operation;
  • Heat treatment;
  • Editing;
  • Grinding operation;
  • Locksmith operation;
  • Package.

Types of blanks for shafts in individual production:

  • round rolled products;
  • forgings;
  • stamping;
  • welded billet from pipes and round bars;
  • square rental.

General information

The following grades of steel are used for the manufacture of shafts: 25, 30, 35, 40, 45; 45G2, 40Х, 35ХС, 40ХС, 35СГ, 30ХН3, 35ХН3М, 45ХН2МФ, etc. Steels 45 and 40Х are most often used. For large shafts and spindles, cast shafts made of high-strength cast iron grade VCh 45-5 (GOST 7293–79) are used. The main requirements for workpieces for shafts are good straightness and the smallest processing allowance. The deviation from the straightness of the workpiece axis should not be more than 0.1...0.15 mm per 1000 mm of length. When straightening on special straightening machines, deviation from straightness can be achieved up to 0.05 mm per 1000 mm. Typical machine setup:

Center designs

Turning centers can have different designs. The most common one is a cone, a workpiece is put on it, as well as a conical shank. The shank must match the holes of the quill and spindle of the machine.

To secure workpieces with external cones, reverse centers are used. The tapered end should coincide with the middle of the shank. To check the coincidence, the center is inserted into the spindle and started at low speeds. The serviceability of the part is indicated by the absence of runout.

The rear center is most often stationary, the front center rotates with the workpiece and spindle. As a result of friction, both surfaces fail, so it is necessary to apply lubricant:

  • chalk - 25%;
  • grease - 65%;
  • graphite - 5%;
  • sulfur - 5%.

Before mixing, it is necessary to grind the sulfur and chalk into powder without lumps. If lubricant is not used, the surfaces of the centers will collapse and their configuration will change.

When turning workpieces at high speeds, the centers wear out faster, and the hole in the end of the part itself increases. To reduce the destruction of the rear cone, a wear-resistant layer is fused onto it.

The standard center is used at speeds up to 120 rpm. When working with bulky and heavy workpieces at high speeds, when removing large chips, the structure has little rigidity: the part begins to vibrate and can be pressed out.

rotating center

Therefore, they use rotating centers mounted in the rear rack. It contains a spindle that rotates in an angular contact bearing. For high loads, a roller bearing is preferable; for medium loads, a ball bearing is preferable.

Heat treatment

To reduce internal residual stresses in workpieces, refine grains and improve machinability with blade tools, forgings and stampings made of high-carbon steels (C > 0.5%) are subjected to heat treatment (annealing or normalization). Annealing is carried out by slowly heating the workpiece over its entire cross-section to temperatures 30–50 °C above the critical point temperature Ac3, holding at this temperature, and then slowly cooling the workpiece together with the furnace. Normalization is carried out by slowly heating the workpiece over the entire cross-section to temperatures 30–50 °C above the critical point Ac3, holding at this temperature and subsequent cooling in air.

Edit

Most workpieces (especially large and non-rigid ones) have shape errors (curvature).
To eliminate curvature, straightening is used (by bending, stretching, heating, etc.). Straightening is an operation to eliminate shape errors (curvature) of workpieces in hot or cold states, carried out manually or using special equipment. Manual straightening of rods and blanks for shafts is straightened in a cold state on manual presses (prisms). Manual editing accuracy can be achieved within 0.05...0.1 mm. Manual straightening is a low-productivity operation, and it is used for small batches of parts, that is, in individual and small-scale production. Mostly, enterprises use machine straightening, carried out on hammers, leveling machines and eccentric leveling presses, as well as on hydraulic presses using special devices. In some cases, workpieces are straightened not only before machining, but also during processing, when, when removing the outer layers of metal, internal residual stresses arise, causing the axis of the workpiece to bend or warp. Blanks in the form of forgings and stampings with significant diameters and lengths are straightened in a heated state under hammers and on eccentric, hydraulic, pneumatic, and friction presses. Before straightening the shafts, the places to be straightened are determined, and the shafts are straightened by placing them on prisms. Table 1—High-quality hot-rolled round steel. GOST 2590-2006. Tolerances for curvilinearity.

Nominal diameter of rolled products, mmCurvature, % of length, no more, for classes
IIIIIIIV
Up to 25 incl.0,20,5Not regulatedNot regulated
Over 25 to 80 incl.0,40,450,5
Over 80 to 200 incl.0,25

Curvilinearity calculator.

Rod length, mm

Curvature tolerance, %

Allowable curvature, mm

Editing is also necessary due to the curvature of the rolled product.
The curvature of the rolled product is measured over a section of at least 1 m in length at a distance of at least 100 mm from the end of the bar. Table 2 - Calibrated round steel. GOST 7417-75. Tolerances for curvilinearity.

Nominal diameter of rolled products, mmLimit curvature depending on the tolerance range
per 1 meter of length, mmfull length, %
h9h10 and h11h12h9h10 and h11h12
Up to 25 incl.1230,10,20,3
Over 25 to 50 incl.0,75120,0750,10,2
Over 500,510,050,1

As can be seen from Table 2, even calibrated steel is not without curvature.

cutting

Cutting is the operation of separating metal into parts. Mechanical cutting is carried out by:

  • mechanical, electric and pneumatic hacksaws;
  • band saws;
  • circular saws;
  • guillotine and disc shears;
  • pendulum saws;
  • abrasive saws.

Hacksaws (powered hacksaws) and circular saws, which are a disk with cutting teeth (very similar to thin cutters), are used for cutting long-form and profile metal and pipes. Cutting is carried out with cooling with oil, water or soap emulsion. Band saws have the shape of an endless strip with a thickness of 1.0–1.5 mm. They are vertical, horizontal and inclined. Band saws are usually used for cutting cast iron, steel, non-ferrous metals and alloys. Losses per cut with a band saw do not exceed 1.8 mm. A friction (toothless) saw is a thin steel disk rotating from an electric motor at a speed of 100–140 m/s. When fed and rotated, due to the resulting friction, the disk heats the metal particles in the slot to the melting point. The molten metal of the workpiece is removed by a friction saw, which is cooled with air and water. Friction saws provide high productivity, but require a high power drive. These saws can cut hardened steel and white cast iron. An electric friction saw is a friction saw with a voltaic arc, which is designed for cutting metal workpieces. The rotating disk is connected to one pole of the electric power source, and the workpiece being cut is connected to the other. Circular pendulum saws are used for cutting profile material, as well as pipes of various diameters. Cutting reinforced grinding wheels mounted on pendulum machines are used for cutting non-metallic and metal workpieces, including hardened steels. In addition to the above methods, rods, pipes and blanks obtained by casting, forging, stamping can be cut on lathes, milling and planing machines.

Centering

When processing external surfaces of rotation (shafts), center holes in parts such as shafts are the basis for a number of operations:

  • turning;
  • thread cutting;
  • grinding;
  • edits;
  • checks.

The correct shape and location of the center holes affect the processing accuracy.
Therefore, the accuracy of parts manufacturing depends on the correct alignment of the ends and the correspondence of the cone angles of the center sockets to the cone angles of the centers of the machines on which the workpieces will be processed. The shape and size of the center holes are regulated by the state standard. Center holes according to GOST 14034–74 are divided into nine types according to shape and purpose. Table 3 - Shapes of center holes and areas of their application according to GOST 14034–74

SketchShape(type)Application areaSymbol
Type A The hole has a cylindrical hole with a diameter d and a cone with an apex angle of 60° without a safety cone.1. In parts, after processing of which there is no need for center holes. 2. In parts that are subjected to heat treatment to a hardness that guarantees the safety of the center holes during operation. Rep. center. A4 GOST 14034–74 (for ⌀4 mm)
Type B The hole has a cylindrical hole with a diameter d and a cone with an apex angle of 60° and a safety conical surface (chamfer) with an apex angle of 120°.In parts in which the center holes are the basis for repeated or repeated use, as well as when the center holes are stored in finished products (the safety chamfer is designed to protect the center holes from damage, as well as to enable end trimming).Rep. center. B6 GOST 14034–74 (for ⌀6 mm)
Type I The hole has a cylindrical hole with a diameter d and a cone with an apex angle of 60°, but instead of a safety cone it has a cylindrical recess of small depth.For mandrels and plug gauges.Rep. center. I8 GOST 14034–74 (for ⌀8 mm)
Type C The hole has a cylindrical hole of diameter d and a cone with an apex angle of 75°.For processing large shafts (for particularly large and heavy parts, the angle is increased to 90°). The purpose is similar to form A. Rep. center. C8 GOST 14034–74 (for ⌀8 mm)
Type E The hole has a cylindrical hole with a diameter d and a cone with an apex angle of 75° (for particularly large and heavy parts, the angle is increased to 90°) and a safety conical surface with an apex angle of 120°.The purpose is similar to form B.Rep. center. E10 GOST 14034–74 (for ⌀10 mm)
Type R The hole has a cylindrical hole with a diameter d and an arcuate generatrix with a radius R.For machining high-precision parts and for machining conical surfaces.Rep. center. R6 GOST 14034–74 (for ⌀6 mm)
Type F The hole has a cylindrical hole with a metric thread and a 60° cone without a safety cone.In parts such as shafts with fastening in the center downwards for installation work, transportation, storage and heat treatment of parts in a vertical position. The thread is designed for screw plugs that are screwed into center holes. Rep. center. F M4 GOST 14034–74 (M4 - metric thread)
Type H The hole has a cylindrical hole with a metric thread and a cone with a tip angle of 60° and a safety conical surface with a tip angle of 120°.In parts such as shafts with fastening in the center downwards for installation work, transportation, storage and heat treatment of parts in a vertical position. The thread is designed for screw plugs that are screwed into center holes. Rep. center. H M6 GOST 14034–74 (M6 - metric thread)
Type P Specially shaped hole with metric thread.For tool cones: Morse, metric, etc.Rep. center. P M8 GOST 14034–74 (M8 - metric thread)

Making center holes in workpieces is carried out:

  • for marking by sequential drilling and countersinking using pneumatic portable machines;
  • on lathes, turrets and drilling machines, with a drill and a countersink forming a conical surface, or a combined tool (center drill);
  • on special one- and two-sided centralizing machines with a drill and a countersink, forming a conical surface, or a combined tool that combines these types of processing (drilling and countersinking);
  • on special milling and centralizing machines.
  • Turning

    The most typical type of parts of bodies of rotation, consisting of a combination of external surfaces (cylindrical, conical, complex shape), is the shaft. Shafts can be made from rolled products, forgings, stamped blanks and castings. The shape of the shafts is: smooth, stepped, eccentric, cranked. By size - small (up to 200 mm long), medium (200 to 1000 mm long) and large (more than 1000 mm long). Workpieces are installed in machine centers or chucks of various types: 3-jaw, self-centering, collet, etc. Processing time should be minimal. When removing an allowance, one proceeds from considerations of a consistent reduction in the rigidity of the shaft, i.e. steps of smaller diameter are processed last. During rough turning, the processing accuracy reaches 14th grade, and the roughness Rz = 40...80 µm. Cutting modes for rough turning:

  • cutting depth 7 mm per side or more;
  • longitudinal feed 0.5 mm/rev or more;
  • cutting speed V = 70…110 m/min when working with a tool with carbide inserts of type VK6;
  • using coolant.
  • Semi-finish turning ensures processing accuracy of 9–12 grade and surface roughness Rz = 10…20 µm. Cutting modes for semi-finish turning:

  • cutting depth 3-6 mm per side;
  • longitudinal feed 0.2–0.5 mm/rev;
  • cutting speed V = 100…140 m/min when working with a tool with carbide inserts type T15K6;
  • using coolant.
  • Finish turning ensures processing accuracy of 7–8 quality and surface roughness Ra = 1.25…2.5 µm. Finish turning cutting modes

  • cutting depth 0.15-1.5 mm per side;
  • longitudinal feed 0.05–0.15 mm/rev;
  • cutting speed V = 150 m/min when working with a tool with carbide inserts of type T30K4, VK2 or VK3;
  • using coolant.
  • Fine (diamond) turning is a finishing processing method. When external turning with diamond (CBN) cutters of non-ferrous alloys, an accuracy of 5-6 grades and a surface roughness of Ra = 0.16...0.32 microns are achieved. Cutting modes for fine turning:

  • cutting depth 0.05-0.1 mm per side;
  • longitudinal feed 0.01–0.03 mm/rev;
  • cutting speed V = 300...3000 m/min when working with a tool with carbide inserts of type T30K4, VK2 or VK3;
  • without coolant.
  • For diamond turning, machines of particularly high precision and rigidity must be used. As a tool for fine turning of steels, you can use wide cutters equipped with plates made of T30K4 hard alloy, and for processing cast iron - cutters with plates made of VK2 or VK3 hard alloy. The front and rear surfaces of the cutting inserts must be brought to a surface roughness of Ra = 0.02...0.04 µm. Fine turning with cutters with carbide inserts is carried out at a depth of cut t = 0.05...0.15 mm, longitudinal feed S = 0.01...0.05 mm/rev and cutting speed V = 200...350 m/min. In this case, an accuracy of 6–7th quality and a surface roughness of Ra = 0.32...0.63 microns are achieved. An emulsion is usually used as a cutting fluid. When processing long, low-rigid shafts, fixed and movable steady rests are used. When processing hollow shafts with controlled wall thickness differences, ring (swivel) steady rests are used.

    Figure 1- a) roller steady, b) vibration-damping steady

    Lunettes serve as additional support that experiences loads. The movable rest, following the cutter, perceives the cutting force. The surface to be treated rests on the cams of the steady rest. In cases where it is necessary to ensure the alignment of the surface being turned with the previously processed one, the cams of the steady rest are installed in front of the cutter, that is, on the previously processed surface. During high-speed cutting, the jaws create significant friction. To reduce friction, steady rests with roller supports are used. During high-speed turning, vibrations often occur, which increase surface roughness and reduce processing accuracy. To eliminate vibrations, steady rests with a vibration damper are used. Belleville springs placed in the vibration damper housing absorb vibrations of the part. At high cutting speeds, the chips have a confluent shape and flow out from under the cutter in a continuous ribbon. Such chips are very dangerous, as they can cause injuries (cuts and/or burns). To crush such chips, special devices are used - chip breakers. In serial and small-scale production, shafts are often processed on CNC machines. In individual production, shaft processing is usually carried out on universal, manually operated equipment.

    Definition and types of turning

    During turning, the cutting tool impacts the part. In this case, two types of movement are performed in the machine - rotational (for the workpiece) and translational (for the cutter). In this way, excess material is removed and the required shape is transferred to the processed component.

    To perform the above operations, the design of the machine has mandatory elements - front and tailstocks, a support and a tool holder. With their help, the tool is positioned relative to the part, and the parameters of certain types of processing are set.

    Depending on the desired result, the following types of turning are distinguished:

    • grinding. Divided into external and internal. Using a cutter, material is removed from the surface of the part;
    • boring. The essence of this function is to increase the diameter or change the configuration of the hole. Special types of cutters are used;
    • turning cones. The operation is similar to the turning procedure, the difference lies in the location of the cutting tool. It is installed at a certain angle relative to the surface;
    • thread formation. This requires a special design of the caliper apron;
    • grooving and cutting. Special types of cutters are used;
    • cutting ends.

    These are the most common types of turning work. They can be performed on one machine, if this is provided for by its design. But to achieve optimal results, you need to know the technical characteristics of the equipment. They affect the quality and accuracy of work.

    If complex processing of parts is expected, it is recommended to use a turret-type tool holder. Several types of processing tools can be located on it; the change occurs due to the rotation of the working head.

    Drilling

    The holes are cylindrical, stepped, conical, shaped. The holes can be open on both sides (through) and on one side (blind). Drilling is a common method for processing blind and through holes in solid material with an accuracy of 12–13 grade and surface roughness Rz = 10…30 µm. Holes with a diameter of more than 30 mm are drilled in two transitions: first with a drill of a smaller diameter, then with the required diameter. There are two drilling methods: with a rotating drill (drilling and boring machines) and with a rotating part (lathes). To reduce drill drift, pre-drilling (centering) is performed with a short rigid drill. Drilling is carried out on lathes and automatic machines, as well as on drilling and boring machines with guide bushings. Drilling machines are divided into universal, specialized and special. On universal drilling machines you can perform any hole processing operations. Universal machines include: vertical drilling, radial drilling, tabletop drilling. Specialized machines include horizontal machines (cartridge and swivel type) for drilling and boring deep holes (swivel machines). If the specified accuracy of the hole is below the 9th grade, then depending on the diameter of the hole and the type of workpiece, subsequent processing is carried out by boring or reaming. The accuracy of the relative position of holes during sequential processing with different tools is achieved using a jig with replaceable bushings and quick-change chucks for securing the tools in the machine spindle. When drilling for threads, the diameter D of the drill is taken to be larger than the internal diameter of the thread d by the amount 2α = 0.3...0.4 of the thread height. Drills are divided into normal, deep drilling and special. Normal drills include spiral, feather and centering drills. For deep drilling (the ratio of hole length to diameter is more than five), feather drills are used. The drill consists of a rod up to 1.5–2.0 m long, which has two grooves for removing chips and two grooves for tubes supplying coolant with high pressure to remove chips. Grooves are made on the cutting edges of the plate to break and crush chips. In addition, this makes it easier for the cutting fluid to remove chips. Such drills are used for holes with a diameter of more than 30 mm. To make deep holes of relatively small diameters - up to 30 mm - twist drills with internal coolant supply are used. However, it is difficult to process deep holes with such a drill, since you have to often remove the drill from the hole to remove stuck chips and, in addition, it is not strong enough and provides less accuracy in the direction of the hole (increased drill drift occurs). Instead of spiral drills, it is advisable to use cannon and gun drills, which do not have a transverse cutting edge, which makes cutting metal easier. The top of the drills is offset by 0.25 diameters, thereby forming a cone that guides the drill. Drilling with such a drill is preceded by drilling to a certain depth with a twist or feather drill, which must be done very carefully to avoid the gun or gun drill being pulled away during subsequent deep drilling. The fairly small chips obtained when drilling with gun or gun drills are easily removed by coolant. The supply of coolant when drilling with a gun drill is carried out under strong pressure through a hole in the drill body, and chip removal occurs along the outer groove of the drill between the body (rod) of the drill and the machined surface of the hole. The disadvantage of gun and gun drills is their relatively low productivity. When drilling deep holes with a diameter of 80 to 200 mm and a length of up to 500 mm, ring drills are widely used. They cut out only an annular cavity in solid metal, and the cylinder-shaped inner part that remains after such drilling can be used to make other parts. Core drills come with several sets of spare HSS blades. Core drills can be used on turning, boring, turret and radial drilling machines that have a conventional coolant supply system. When drilling with such drills, productivity increases up to 4 times compared to drilling with twist or gun drills.

    Figure 2 - Ring drilling

    Countersinking is used to process a previously prepared hole by casting, broaching or drilling. The tool is a countersink. Countersinks, depending on their purpose, are divided into cylindrical and conical. Reaming is the main method of processing a hole of the 8th–9th accuracy grade (when processed with two reamers, the 5th–7th accuracy grade is reached) with a surface roughness Ra = 0.15...2.5 µm in a material with hardness HRC ≤ 40. Reaming – differs from a countersink in a larger number of teeth and smaller angles in the plan. Reamers are divided into manual and machine and are made solid and sliding. Hand reamers have long teeth and a long tapered part called a fence. Machine one-piece reamers are used for holes with a diameter of up to 30 mm. For holes with a diameter of more than 30 mm, in order to save cutting tool material, attachment reamers are used. Sliding reamers are used for diameters from 25 to 100 mm. Reamers with insert knives are widely used, used for diameters from 35 to 150 mm. A necessary condition for achieving high machining accuracy is the uniformity of the allowance removed and strict coincidence of the reamer axis with the axis of the hole being machined. During operation, the reamer must be freely positioned along the hole or have an accurate direction. When working with finishing reamers on lathes and turret machines, oscillating mandrels are used to compensate for the mismatch between the hole axis and the direction of the reamer.

    MANUFACTURING SHAFT. ROUTE TECHNOLOGY

    In the first part of the technological process (operations No. 10 – 40)

    ensures the formation of a preliminary contour of the workpiece on

    high-performance turning equipment. The first part of the technical

    The nological process can be divided into three main stages:

    first stage (operations No. 10 – 15) – treatment of the internal cavity

    shaft on lathes and preparation of technological bases for following

    next stage;

    second stage (operations No. 20 – 30) – formation of the external contour

    ra wala. These operations are performed on prepared databases using the method

    turning;

    third stage (operations No. 35 – 40) – removal of internal stresses

    by heat treatment and preparation of base surfaces

    for high-quality processing in the next part of the technology

    gical process.

    In the second part of the technological process (operations No. 45 – 115)

    semi-finishing of the main surfaces of the shaft is carried out and

    a shaft profile is formed that is close to the profile of the finished part. Important

    The purpose of this part of the technological process is to ensure

    determining the exact location of the shaft surfaces relative to each other

    and prepared base surfaces. In this part the technological

    of the process, quality control is also carried out

    basic parameters of workpieces.

    In the third part of the technological process (operations No. 120 -

    175) quality indicators of the shaft are provided for the main

    surfaces. These operations are performed on a high-precision turning machine

    and grinding equipment. Much attention in this part of technology

    logical process is given to creating and maintaining good

    condition of basic technological surfaces.

    In the fourth part of the technological process (operations No. 180 -

    335) working parameters are formed using final finishing methods

    and design surfaces. In this part of the technological pro-

    During the process, finishing and final inspection of the rotor shaft are carried out

    GTD.

    The machining plan for the initial workpiece is as follows:

    this sequence.

    First part

    No. 5. Stamping.

    No. 10–15. Pre-turning of the internal contour

    shaft

    188

    No. 20–30. Pre-turning of the outer contour

    shaft

    No. 35-40. Preparation and control of base surfaces.

    Second part.

    No. 45–80. Semi-finish boring of the inner contour of the shaft, removal

    stresses, control and preparation of base surfaces.

    No. 85–100. Finish turning of the shaft “stem” and preparation

    external base surfaces.

    The third part.

    No. 105–115. Final turning of flange and internal

    th circuit.

    No. 120–125. Grinding of internal cylindrical surfaces.

    No. 130. Polishing the inner contour and shaft cone.

    No. 135–140. Washing and quality control.

    No. 145–150. Diamond smoothing of the internal surfaces of the shaft.

    No. 155. Final processing of the outer shaft profile.

    No. 160. Machining holes in the flange.

    No. 165–175. Grooving of labyrinth seals and grooves. Grinding

    formation of external base surfaces. Quality control

    founders of the shaft.

    Fourth part.

    No. 180–195. Processing of the technological sample, its installation on the

    Lu, chiselling and grinding slots on the sample.

    No. 200–215. Machining the spline on the shaft.

    No. 220 Machining of the shaft.

    No. 225 Control.

    No. 230–240. Shot blasting and finishing of surfaces

    slot.

    No. 245–270. Milling small recesses and machining depressions and

    holes by drilling and countersinking.

    No. 275. Metalworking.

    No. 280–290. Magnetic control of shaft material.

    No. 295–310. Removing internal stresses and modifying the shaft during service

    whenever necessary.

    No. 315–335. Final control of the quality indicators of the shaft.

    Let's consider the implementation of individual technological operations

    manufacturing process of gas turbine engine shafts.

    The first part of the mechanical machining process

    boots (Fig. 5.5) provides for preliminary, rough processing

    189

    shaft During surgery

    No. 10 the initial workpiece is installed on the lathe

    machine type 1D63 on prepared external base surfaces

    nesses with the help of roller steady rests, is oriented in the axial direction -

    control along the small end of the shaft and is driven by a four-cylinder

    lachka cartridge. This operation involves boring the internal

    its contour, cylindrical belts and conical shapes are formed

    yawning. During the processing process, significant allowances are removed.

    Removal of allowances is carried out in several passes. Treatment

    carried out at cutting speed v = 60...70 m/min., longitudinal

    feed in this case S

    o = 0.6 mm/rev. To bore holes, use

    straight boring cutters with the following basic geometrical

    Chinese parameters: ϕ = 45°; ϕ1 = 45°; ã =12°; á = 10°; ë= 2°. Radius y

    cutter apex r

    = 1 mm. The cross-section of the cutter holder is 25×25 mm.

    The cutters are installed and fixed in a special frame (bur

    barbell). A hole with a diameter of 258+0.6 mm and the end of the flange on this op-

    walkie-talkies are prepared as bases for subsequent processing.

    During surgery

    No. 15, the workpiece is installed in a three-jaw pa-

    throne along a bored belt with a diameter of 258+0.6 mm and is oriented in

    axial direction along the end of the shaft flange. The other end of the shaft is installed

    poured in the technological system using a roller rest,

    which is fixedly fixed on the machine bed. On this operation

    a hole is bored in the “stem” of the shaft. Hole diameter

    is 86 mm, and the boring length is more than 1000 mm. When machining a hole

    the allowance removed is uneven, which is determined by the feature

    manufacturing the original workpiece. In some cases, this unequal

    the size of the allowance may appear as “blackness” in the middle part

    hole being processed.

    When performing this operation, preparation is also carried out

    basic mounting chamfer, which is bored at an angle of 30°.

    Boring is carried out at low machining conditions in order to ensure

    ensuring high quality chamfer surfaces. An important condition for

    chamfer boring is to ensure alignment of the chamfer axis with the axis

    holes with a diameter of 86 mm, as well as creating a chamfer shape with mini-

    small deviation from nominal values.

    Subsequent operations No. 20 and 25 are performed on prepared

    basic installation surfaces and provide for processing

    outer contour.

    190

    Rice. 5.5. Preliminary stage of shaft processing

    191

    During surgery

    No. 20, the main allowance is removed, removal is carried out

    cutting technological samples (see Fig. 5.3). Machining allowance

    various surfaces fluctuates within significant limits and removes

    takes place in several passes.

    Setting operational dimensions in technological operations

    process provides the possibility of their execution on a configured

    machine in semi-automatic mode. One size (12±0.4 mm) sets -

    relative to the installation base, and the rest provide internal

    complex dimensional relationship of the processed surfaces. Ope-

    walkie-talkie No. 20 is carried out on a high-performance lathe

    1D63. Cutting speed – v

    = 60 m/min, longitudinal feed
    S
    o = 0.6

    mm/rev. During processing, surface roughness is achieved up to

    Rz80. Tolerances for linear dimensions are within 1.2 mm, and

    for diametrical dimensions - from 0.53 to 0.68 mm.

    Operation No. 25

    carried out after quality control carried out

    on a high-performance lathe mod. V-800NC

    "BOEHRINGER". This operation involves grooving the outer

    shaft contour, preliminary groove formation is performed,

    protrusions, labyrinth shelves and other important structural elements

    tions.

    In this operation, the workpiece is installed according to the prepared

    previously to base surfaces. After cutting the girdle on the outer

    surface, which is strictly consistent with the installation chamfer, produced

    additional installation of the shaft along the steady rest is carried out. This way of originating

    placement of the workpiece in the technological system makes it possible to ensure

    ensure the reliability of processing the shaft surfaces in this technical operation

    nological process.

    At operation No. 30

    the workpiece is installed along two cylindrical

    sky surfaces prepared for rests. These surfaces

    strictly orient the workpiece in the technological system. After tired

    When new the workpiece, its position is checked. Acceptable

    The runout during installation should not exceed 0.03 mm. At this opera-

    tion, the large shaft flange is pre-treated and

    inlet contour of the hole from the flange side. In this part of technology

    gical process, the allowance for subsequent processing is reduced

    and its uniform location relative to each other is created.

    Cutting speed v

    = 60 m/min, and longitudinal feed

    S

    o = 0.2 mm/rev. The roughness of the processed surfaces is

    equal to Rz

    20.

    192

    Operations No. 35 and 40

    (control of base surfaces) are performed

    in order to create precise mounting surfaces for further

    carrying out a set of operations to improve the quality of

    procurement indicators. In this case, a finishing grooving of the ci-

    lindrical belts with an accuracy of 0.05 mm, ensuring their bi-

    relative to each other and the bored collar in the hole is not

    more than 0.02 mm.

    The roughness on the base belts is not lower than Ra

    3,2.

    The obtained parameters are carefully checked by control

    measuring instruments.

    Thus, when processing the original shaft workpiece in the first

    As part of the technological process, the following work was performed:

    1) basic pre-processing of internal and

    external contour of the workpiece, internal thermal stresses are removed

    chemical processing and checked the quality of the material in accordance with

    first control group;

    2) uniform distribution of the allowance along the formation is ensured;

    surfaces for further processing of workpieces.

    3) technological installation surfaces have been prepared (ba-

    PS) for high-quality further processing of the shafts.

    The second part (Fig. 5.6) of the manufacturing process

    shafts (operations No. 45–100)

    provides for a gradual increase

    maintaining accuracy in operations and bringing the workpiece contour closer to

    outline of the finished part. In this part of the process

    it also provides for the removal of internal stresses, resulting

    at previous stages of processing and careful control

    changes in the geometric parameters of workpieces. An important condition

    to eliminate possible warping of workpieces during thermal

    processing is the vertical position of the shaft during the inspection process

    details of this operation.

    Updating the basic installation surfaces (belts and facades)

    juice) is carefully controlled, and errors are eliminated by

    alignment and modification of shaft installation elements.

    After grooving the outer cylindrical base

    surfaces (operations No. 65) and quality control of these

    surfaces are finished boring a deep hole

    using a boring head.

    193

    Rice. 5.6. Semi-finishing stage of shaft processing

    194

    Operation No. 75

    – hole boring, performed with high precision

    Nominal lathe B-630 "BOERINGER". Blank, installed-

    fitted into roller rests and aligned along the outer cylindrical

    surface up to 0.02 mm, drives the four-jaw

    new cartridge. The cutting head receives a strict relative direction

    specifically the special guide system of the machine. This system is

    allows you to ensure minimal displacement of the axis of the boring

    version relative to the nominal position. At boring depth

    ki 1426+1.5 mm hole runout relative to installation

    surfaces does not exceed 0.05 mm. Bored hole diameter

    this provides 107.95+0.05 mm. Surface roughness

    is Rz20.

    After installation, monitoring and checking the position of the base surfaces

    In this case, a hole with a diameter of 95.95+0.05 mm is processed with

    the opposite side of the shaft (operation No. 85). By doing

    In this operation, the workpiece is also installed in the roller rests

    and is driven from the machine spindle using a four-piece

    pocket cartridge. During the installation of the workpiece in the technological

    This system controls its position. The beating should not exceed

    embroider 0.02 mm.

    Operations No. 90 and 100

    provide semi-finish processing

    outer contour and creation of basic mounting surfaces

    for the finishing stage of shaft processing.

    Very important operations when processing internal software

    shaft cavity are boring deep holes (operation No. 45, 75,

    85) using boring heads. The quality of these operations

    radios largely depends on the performance of the rotor part of the gas turbine engine.

    When boring, it is necessary to ensure hole size and accuracy

    its location relative to the base mounting surfaces.

    Displacement of the hole being machined relative to the nominal one

    position in preliminary operations leads to an increase

    allowance for final processing of the shaft, and the increased offset

    boring hole in the final technological operations

    process - to the appearance of imbalance of the shaft elements

    relative to design base surfaces.

    195

    Rice. 5.7. Diagram of boring a hole from the shaft flange side (operation No. 45)

    196

    Operations No. 45

    – boring of the central hole from the flange side

    The shaft assembly is performed on a lathe B-630 mod. "BOERINGER"

    (Fig. 5.7). Shaft blank 2

    installed in the technological system

    machine along two basic sections (b-b, s-c)

    on movable rests. Ba-

    zoning is carried out on two rotating rollers, which

    placed in movable shoes 16

    and
    18
    lunette. When setting up an operation

    these shoes are brought to the center by the rotation of the screw 15,

    providing

    centering the workpiece relative to the machine spindle and chuck 1.

    Upper pressure roller 17

    brought to the workpiece for fixation

    position using the handle 11.

    Pressing the workpiece to the rotating

    The rollers are rotated after turning in the transverse direction

    slats 12

    and securing it to the steady rest with clamp
    13.
    Installing the shaft in

    the technological system must ensure strict arrangement

    it in the transverse direction relative to the axis of rotation of the spindle

    machine and boring bar axis 5.

    After installing the shaft in the steady rests, the position is checked

    it in the technological system. During the preliminary operation (opera-

    tion No. 45) the permissible runout is 0.05 mm., and for semi-finish

    operations (operations No. 75, 85) the runout should be no more than 0.02 mm.

    After checking the specified conditions for the location of the shaft in the

    in the river direction using indicator watches is carried out

    jaw supply 9

    and
    10
    four-jaw chuck
    1
    and reliable

    fastening the workpiece. An important condition when securing the workpiece

    is to fix it without distorting its initial position.

    The machine spindle provides rotation (nzag.). Boring rod 5,

    mouth-

    updated in guides 6-8

    machine, carries out smooth movement

    Cutting head 14

    in the longitudinal direction (arrow
    A).
    This

    movement is ensured by a special hydraulic system of the machine

    ka.

    Thus, in the second part of the technological process,

    The following works are not required:

    1) semi-finishing of the shaft was carried out and the accuracy of the equipment was increased

    new surfaces;

    2) the geometric parameters for the os-

    new free shaft surfaces;

    3) the exact location of the shaft surfaces relative to

    but technological basic installation surfaces;

    4) basic mounting surfaces have been prepared for further

    neck processing:

    197

    – center chamfers are prepared for processing the outer contour

    and internal cylindrical belts;

    – external circuits have been prepared for processing the internal contour;

    lindrical belts for lunettes.

    The third part of the technological process (operations No. 105–175)

    provides finishing treatment of critical surfaces of the

    la on lathes and grinding machines (Fig. 5.8). In this part of the techno-

    logical process operations are carried out to process complex

    high-precision shaped surfaces, labyrinthine shapes are formed

    seals, improves the quality of shaft surfaces for

    due to smoothing, polishing and other technological methods.

    Operation No. 105

    provides for final turning

    the side of the large shaft flange and the conical generatrix of the internal

    contour.

    On operations No. 110–115

    secondary boring of the hole is carried out

    shaft from the flange side. Processing is carried out with a boring head -

    on the B-630 BERINGER lathe. When boring diameter

    the hole increases to 108.7+0.054 mm.

    Operations No. 120–150

    provide for final processing

    internal cavity of the shaft: grinding, diamond grinding

    living and polishing the internal contour. At the same time it improves

    qualitative condition of the surface layer and is ensured by increased

    reducing the service life of shafts during operation.

    The location of the internal contour of the shaft relative to the basic technical

    technological surfaces in these operations are ensured with high

    what precision. Displacement of the internal contour of the shaft relative to the new

    the minimum position should not exceed 0.025 mm. This character

    Precision statistics allow for minimal mixing of masses

    shaft elements relative to the axis of rotation during operation and improvement

    determine the conditions for balancing the rotor part of the gas turbine engine.

    On operation No. 155

    final turning is carried out

    main surfaces of the outer contour of the shaft. Outer offset

    shaft contour relative to the nominal position is carried out in

    range from 0 to 0.02 mm.

    198

    Rice. 5.8. Finishing stage of shaft processing

    199

    Fig.5.9. Finish turning of labyrinths, thread cutting and preparation

    Grinding

    Grinding is the main and most common method for processing external cylindrical surfaces. Divided into fine and fine grinding. Fine grinding is carried out with grinding wheels or grinding belts on cylindrical grinding machines with longitudinal feed and the plunge method, on centerless grinding machines with a pass and the plunge method, as well as on belt grinding machines. On a cylindrical grinding machine, the workpiece is mounted at the centers of the machine. The linear speed of the rotating workpiece is 10–15 m/min, and the linear speed of the tool (grinding wheel) is about 30 m/s. The grinding process can be carried out with longitudinal feed and plunge method. In the first case, the workpiece undergoes reciprocating longitudinal movement with longitudinal feed Spr = (0.5 – 0.8) N, where H is the height of the circle, per revolution of the workpiece, and at the end of each stroke a transverse feed is made (depth of cut) 0 .01–0.03 mm. During nursing passes, the longitudinal feed is reduced to Spr = 0.2...0.3N, cutting depth to 0.005...0.02 mm. The length of the longitudinal stroke during grinding should ensure that the tool overtravels to one side equal to 0.2 - 0.4 N, where N is the height of the wheel or the width of the belt. The second method is that the tool (grinding wheel or sanding belt) is only given a transverse feed per revolution of the workpiece. Finish cylindrical grinding at the centers of the machine ensures 6–7th grade accuracy and surface roughness Ra = 0.3…1.25 µm. Fine cylindrical grinding in the centers of the machine ensures accuracy of the 5th–6th grade and surface roughness Ra = 0.02…0.08 microns. When grinding on pass-through centerless grinding machines, the workpiece is placed between two grinding wheels on a special supporting knife made of wear-resistant material. Thanks to the bevel directed towards the drive circle, the part is pressed against the drive circle, as a result of which the drive circle transmits torque to the part. To avoid cutting, parts with a diameter of more than 30 mm are shifted upward by 10–15 mm from the line of the centers of the grinding wheels. When grinding on a pass, the driving wheel is set at an angle α = 1...5°. The amount of longitudinal feed S during grinding per pass is prescribed in the range of 400–4000 mm/min. Linear speed of the driving wheel Vв.к = 15…30 m/min during rough grinding. When finishing grinding, increase to 100 m/min or more.

    Characteristics of turning methods

    Turning of cylindrical surfaces (Fig. 10, a–c) is carried out with straight or bent cutters with a longitudinal feed movement.

    Rice. 10. Basic schemes for processing workpieces on a universal screw-cutting lathe : a–c – turning of external cylindrical surfaces; d – cutting the ends; d, f – turning straight and shaped grooves, respectively; g – cutting; h, i – boring of smooth and stepped holes, respectively; j – drilling; l – thread cutting; m – turning of cones with transverse feed; n, o – turning short and long conical surfaces, respectively; α – angle of rotation of the workpiece axis; Dr – cutting movement; Ds – feed movement

    In this case, various through cutters are used in order to obtain transition surfaces of different shapes. Usually, before turning the outer surfaces, the ends of the workpiece are trimmed (Fig. 10, d). Processing is carried out using scoring cutters with a transverse feed movement towards or away from the center of the workpiece.

    When cutting towards the center, the end turns out to be slightly concave; when cutting from the center, the end turns out to be slightly convex, and the surface roughness is less.

    Grooving (Fig. 10, e, f) is carried out with a transverse feed movement using special cutters, in which the shape and dimensions of the main cutting edge correspond to the groove being machined.

    Cutting off the processed part (Fig. 7.10, g) is carried out using cutting tools with a straight or inclined main cutting edge. In the latter case, the end of the cut part is cleaner.

    Boring of internal cylindrical surfaces is carried out using boring cutters fixed in a tool holder in the direction of the workpiece axis, with longitudinal feed. Boring of smooth through holes is carried out with through cutters (Fig. 10, h), and stepped and blind holes - with persistent boring tools (Fig. 10, i).

    Drilling, countersinking and reaming of central holes (Fig. 10, j) are performed with an appropriate cutting tool. Thread cutting (Fig. 10, l) is carried out with special thread cutters. The shape of the cutting edges of the cutters is determined by the profile and cross-sectional dimensions of the thread being cut.

    Processing of conical surfaces can be carried out in several ways. Wide turning cutters with longitudinal or transverse feed movement (Fig. 10, l) are used to chamfer or obtain surfaces with a length of no more than 30 mm.

    By moving the tool at an angle to the axis of rotation of the workpiece (Fig. 10, n), processing is carried out with manual feed of the cutter. The length of the cone generatrix processed in this way does not exceed 100–150 mm. By turning the axis of rotation of the workpiece at an angle  of no more than 8° (Fig. 10, o), long conical surfaces are processed.

    Features of processing heavy engineering parts

    Heavy engineering includes the production of metallurgical equipment (for example, rolling mills), large metal-cutting machines, powerful hydraulic, steam and gas turbines, electric generators, large excavators, etc. Processing techniques used in heavy mechanical engineering are also used when processing large parts at factories in other branches of mechanical engineering and partly in workshops for processing basic parts in medium-sized mechanical engineering. Since large machines are manufactured in very small quantities, production is organized as single or small-scale production. In the manufacture of large machines, universal equipment and simpler technological equipment are most often used than in mass production. Due to the large weight of large workpieces and parts (up to 300 tons), intra-shop transport becomes of great importance. The main means of transport in heavy engineering workshops are usually overhead cranes, the lifting capacity of which reaches 250 tons and above. In some cases, particularly heavy parts are lifted and moved by two cranes at the same time. When designing heavy machine tools, efforts are made to avoid moving heavy parts from operation to operation and during processing. For this purpose, mobile portal machines with milling heads, mobile boring columns, single-sided milling machines in which a milling cutter with a diameter of up to 2 m has a feed, large rotary machines for turning parts with a diameter of up to 18 m, heavy multi-slide lathes for turning parts up to 30 m in length are used. and with a diameter of up to 2 m. In the course of the development of heavy engineering technology, a system of so-called “bench processing” was developed, that is, if the processing machines are lighter than the workpiece, then it is easier and cheaper to move the machine to the workpiece than the workpiece to the machine. Bench processing is carried out using horizontal drilling and boring and portable machines moving along the stand, supplied to the stand by a crane. Portable machines are used: drilling machines - with a drilling diameter of up to 60 mm, radial drilling machines - with a drilling diameter of up to 75 mm, cross-planing machines - with a slide stroke of up to 1500 mm, slotting machines - with a slide stroke of up to 2000 mm. When manufacturing basic parts (beds, frames, frames, etc.), combined bench processing accounts for up to 60% of the total labor intensity and reduces the processing cycle by 1.5–2 times. When bench processing, adhere to the following rules.

    • The time for installing each additional mobile or portable machine to the parts should be less than the time required to reinstall the workpiece on another machine.
    • Mobile and portable machines should be placed around the part so that parallel operation of the machines can be organized and the machine on which the work has been completed can be removed without interfering with the work of other machines.
    • Heavier mobile machines must handle more work than lighter portable machines.
    • The technological process maps must contain all the necessary instructions about the procedure for processing with mobile, portable machines and how to install them on the stand.
    • All necessary equipment for mobile and portable machines should be prepared. It must be submitted to the stand simultaneously with the machines.
    • While a part is being processed at one place on the bench, another workpiece is being prepared for processing at an adjacent place on the bench.

    To improve the conditions for processing heavy parts, additional equipment (improvement) of the workplaces of universal machine tools is used, the purpose of which is to expand the technological capabilities and improve the use of the equipment.
    Additional pits and ditches are installed near the machines, in which workpieces that do not fit on the machine plate can be processed. Additional plates are made on radial drilling machines, on which it is possible to prepare the processing of one workpiece while processing another. Radial drilling machines are mounted on a trolley that moves along a long workpiece. Figure 3 - Construction of a hole on a radial drilling machine

    Machine tooling for turning

    In addition to the main components of the equipment, in some cases special equipment will be needed to perform turning work. It can be included as standard on the machine, or installed as an option. In this case, turning can be performed in non-standard modes.

    One of the defining components is the parts fixation mechanisms. Traditionally, the workpiece can be mounted between the headstock and the rear drive stock. This takes into account the configuration of the locking chuck, as well as the parameters of the tailstock quill.

    To increase the functionality of the equipment, the following additional components of the lathe can be used:

    • clamps. Designed to transmit torque when securing parts in centers;
    • pressure Installed on the tool holder and is necessary to increase the accuracy of tool positioning;
    • lunette. Used for turning work with large workpieces. This device serves as an additional fixing element.

    In addition to these devices, various others can be used. It all depends on the requirements for the quality of operations, as well as the parameters of the processing flow chart.

    As an example, you can watch a video that shows high-tech turning of a part:

    Rating
    ( 2 ratings, average 4.5 out of 5 )
    Did you like the article? Share with friends:
    For any suggestions regarding the site: [email protected]
    Для любых предложений по сайту: [email protected]