Course project on "Development of KS11 machine speed box"

Contents

Introduction

Justification of machine performance

Description of machine process capabilities

1.2. Definition of allowances

1.3. Defining Cutting Depths

1.4. Determination of limit cutting speeds

1.5. Determination of control range, denominator

row and number of drive stages

1.6. Calculation of effective power and selection of electric motor

2. Kinematic calculation

2.1. To Create a Structural Grid for a Main Motion Drive

2.2. Development of machine kinematic diagram

2.3. Plot Rotation Speeds

2.4. Determination of gear ratios and calculation of tooth numbers

gears (pulley diameters)

2.5 Calculation of permissible error of rotation speeds

and actual stage errors

3. Strength calculations

3.1 Calculation of the module on the condition of bending strength and

by allowable contact voltages

3.2. Approximate calculation of drive shaft diameters

3.3. Calculation of shaft for complex resistance

3.4. Calculation and selection of bearings

3.5. Calculation of spline connection

4. Description of the kinematic diagram and layout of the machine, structural features of lubrication of the main units

5. Conclusions and conclusions

6. Bibliographic list

Project Description

In the course work, the kinematic calculation of the main motion drive is given with the construction of the structural grid, the development of the kinematic drive scheme, the selection of the engine, the construction of the rotation speed graph, the determination of gear ratios, the calculation of the numbers of gear teeth, the calculation of the permissible error of rotation speeds and actual errors at all stages. The work also contains strength calculations, which include the calculation of the module, the calculation of shaft diameters is indicative, for complex resistance and refined; selection of bearings, calculation of splined joint, etc.

Introduction

Modern engineering is impossible to imagine without high-quality equipment and technological equipment. Today's machines are a new generation of process equipment, providing high processing accuracy and quality of machined surfaces.

The nomenclature of machine tools is huge. They are classified by type (turning, drilling, milling, stretching, etc.), by type (single and multi-spindle, automatic and semi-automatic), by accuracy class (normal, advanced, high accuracy).

The vertical milling machine 6H12 was chosen as the base machine.

Justification of machine technical characteristics

1.1 Description of machine process capabilities

The machine is intended for milling of various details from steel, cast iron and non-ferrous metals by disk, shaped, angular, face, trailer and other mills in the conditions of individual and mass production. The possibility of adjusting the machine to various semi-automatic and automatic cycles allows you to successfully use the machine to perform work of an operational nature in in-line and automatic lines in large-scale production.

The machine can handle vertical and horizontal planes, slots, corners, frames, gears, etc.

Technological capabilities of the machine can be expanded using a dividing head, a rotary round table, an overlay universal head and other devices.

Description of the kinematic scheme and layout of the machine, structural features

Main Motion Circuit

From a 7.5 kW motor, motion is transmitted to the first shaft by a gear train. All gears of the speed box are mounted on six shafts and a spindle, which are installed on rolling bearings. From the first to the second shaft, rotation is transmitted using a gear. Further, from the second to the third shaft - with the help of a triple block of gears. Then, from the third shaft, using gears, rotation is transmitted to the fourth shaft. From fourth to fifth - using a double block of gears. Then from the fifth to the sixth by means of conical transmission. Rotation is supplied to spindle from sixth shaft through pairs of gears. The different positions of the gear units of the gearbox allow for 12 different speeds on the spindle.

The spindle rotation numbers are changed due to the movement of gear blocks along splined shafts using two handles brought to the front wall of the speed gearbox. Braking is performed by brake clutches.

Speed box

Spindle revolutions vary by moving gear blocks along splined shafts.

The speed box allows the spindle 12 to communicate at different speeds, which is accomplished by different combinations of engagements. The given number of revolutions make up the standard series.

The speed box is mounted on the frame body. It is controlled by a shift box located on the left side of the frame.

Braking is performed by brake clutches.

Feed drive box.

The feed is driven by a separate 1.425 kW flange motor. Through transmissions 26/44 and 24/64, the feed box shaft XI is rotated. On the shaft XI is a triple movable gear block communicating three rotational speeds to the shaft XII by means of gears 36/18, 18/36, 27/27.

On the shaft XIII there is a triple movable unit, by which the movement from the shaft XII to the shaft XC can be transmitted by three versions of gears 18/40, 21/37, 24/34. Therefore, shaft XIII has nine different revolutions (3X3 = 9). When the movable cam gear 40 at the end is moved to the right and engaged with the clutch rigidly coupled to the shaft XIII, rotation from the shaft XIII to the shaft XIV is directly transmitted. If the gear 40 meshes with the gear 18, thereby turning off the clutch, then movement to the shaft XIV will be transmitted through the overrun 13/45 * 18/40. In this case, too, it works as a downshift .

Thus, the machine feed box has eighteen different feeds: nine when working without overrun and nine when working with overrun (9X2 = 18). From the wide gear 40, rotation is transmitted to the shaft XIV through a safety clutch with the cam clutch on, and from the shaft XIV through a gear 36/27 to the shaft XV .

From shaft XV, it is possible to transmit all 18 revolutions to the longitudinal, transverse and vertical feed propellers. Longitudinal feed of table is performed from shaft XV along kinematic chain 18/33. 33/37 to shaft XIX, then through transmission of bevel gears 18/16 to shaft XX, from shaft XX to lead screw of longitudinal feed through bevel gears 18/18 and cam clutch .

Transverse feed is communicated from shaft XV through gears 18/33 and 33/37 with clutch on to table. Through the 18/33 transmission, when the coupling is turned on, it is transmitted from shaft XV to shaft XVI and further through gears 22/33, conical transmission 22/44 to the vertical feed lead screw XVIII. The value of the highest vertical supply.

Values of longitudinal, transverse and vertical minute feeds of machine tools of M series are taken according to the same geometric row with denominator a = 1.26, as for spindle rpm numbers. Number of innings 18. Quick movements of the table in all directions are carried out with the friction clutch turned on. In this case, rotation from the feed motor with a power of N = 1.425 kW, bypassing the feed box, is transmitted to the shaft XIV through the gear train 26/44, 44/57, 57/43 and further along the kinematic feed circuits. Manual movements of table, cross slides and cantilever are performed by flywheels and handle, respectively. For ease of control in the machine, longitudinal movement of the table can be carried out by a flywheel, which is connected to the longitudinal feed lead screw XXI through the gear wheels 24/23, the cam clutch and the gear train 24/23. Cam couplings are locked. Movement of the spindle together with the sleeve is carried out by the handwheel. The lead screw IX transmits movement to the nut rigidly fixed on the spindle sleeve.

Spindle

A spindle is used to rotate the cutting tool, which receives movement from the speed box. The accuracy of the spindle production, its strength and rigidity depends on the accuracy of rotation of the mandrel with the cutter worn. The milling machine spindles are made of 40X alloy steel and heat treated.

The spindle of the machine has high requirements for the cleanliness and accuracy of machining of this part. Spindle is made hollow.

For its accurate operation, accurate bearings are used. The machine has two roller bearing supports .

Bearing journals are machined according to the 1st accuracy class so that the spindle rotation is correct. Very precisely, the front end of the spindle and the conical seat should be treated - places for installation and attachment of tools and mandrels.

Domestic milling machines have a standard front end of the spindle.

Machine base

The base of the machine is cast from gray cast iron and precisely straddles on both sides. On one side of the base is installed and fixed by bolts of the machine bed; the other side adjoins the floor of the shop. In the base there is a trough for cooling liquid, which flows down the tubes from the table. Electric pump for cooling liquid supply to tool is mounted on base.

Bed

The frame serves for attachment of all units and mechanisms of the machine. Some components of the machine (speed box, belt motor, motion transmission mechanism to the feed box and spindle of the machine) are located inside the frame and are not visible. Other components of the machine (cantilever, feed box, trunk, table, coolant pump) are located on the external surfaces of the bed.

The bed is box-shaped and reinforced from the inside with ribs; on its front wall there are vertical guides (made in the form of a "dovetail") for the cantilever, and on top - horizontal guides for the trunk.

The frame is the main part of the milling machine and is manufactured exactly according to the drawing and specifications. It is cast from high-quality cast iron and is carefully processed.

Console

The cantilever is a rigid cast iron cast installed on vertical guides of the bed. Cantilever moves along vertical guides of frame and carries horizontal guides for slides. It is supported by a post in which a telescopic screw is located for lifting and lowering the cantilever. The rigidity of the cantilever structure and the accuracy of its guides are of paramount importance for the operation of the machine. In the console there are two bolts that attach supports that connect the machine table with the proboscis for better stability under high loads.

Sled

Slides are intermediate link between cantilever and machine table. Table moves along upper guides of sled in longitudinal direction, and slides themselves move in transverse direction along upper guides of cantilever.

Table

The table is mounted on the slide guides and moves in the longitudinal direction. Workpieces, clamping and other devices are fixed on the table, for which the working surface of the table has longitudinal T-shaped slots.

The movement of the table, skid and cantilever imparts a longitudinal, transverse and vertical feed to the workpiece with respect to the cutter.

Manual or mechanical feed can be used for installation movements during adjustment and for idle runs of the table, and only mechanical feed can be used for work feeds.

In addition to working feeds, on most milling machines, the table has a fast travel (accelerated movement) in all three directions. A quick stroke is provided to feed the workpiece to the mill, as well as to move the table back.

The fast stroke is carried out at one constant speed, and the working feeds have several stages, which can be installed using the feed box depending on the processing nature, the material of the cutter and the workpiece.

Lubrication of speed and feed box

Lubrication of the speed box is carried out from a plunger pump driven by an eccentric. The pump capacity is about 2 l/min. Oil is supplied to the pump through the filter. Separate tubes are connected to front bearing of spindle and eye of pump operation control.

Lubrication of the switching box is carried out from the speed box lubrication system by spraying oil coming from the tube in the upper part of the bed. The absence of oil rain can cause unacceptable heating of the cheeks of the switching forks and lead to jamming of the forks, their deformation or breakdown.

Conclusion

After making calculations, a vertical milling machine was designed. The designed machine is a more modernized model, as it can transmit 12 different speeds to the spindle, from 250 rpm to 3150 rpm.

Machines of this type are used both in single and in small and large-scale production.

This machine, designed on the basis of the 6H12 vertical milling machine, meets all technological, structural and operational requirements.