Design of vertical cantilever-milling machine 6P12 feed box.

Contents

Contents

Purpose of the course project

Introduction

Milling machines;

Description of the machine;

Feed box;

Speed switching mechanism;

Technical characteristics;

Kinematic calculation

Electric motor selection

Adjustment of machine bearings

Gearing calculation

Shaft preliminary calculation

Shaft check calculation

Calculation of splined joints

Calculation of bearings

Description of electrical circuit operation

Lubrication of the machine

Conclusion on the work done

List of used literature

Purpose

Design the supply box of the vertical cantilever machine 6P12.

Study the characteristics and purpose of the machine

Perform kinematic calculation

Select Motor

Perform check calculations of shaft, gears and bearings

Study the principle of operation of controls

Study the electrical diagram of the machine

Maintaining

Milling machines

The milling machines are characterized by an actuating shaping motion consisting of a continuous rotational movement of the tool defining the cutting speed and a rectilinear, circular or helical feed motion. At the same time, the feed movement is communicated to the workpiece, less often, to the tool .

On milling machines, planes, shaped surfaces (dies, cams, etc.), surfaces of rotation, external and internal threads, screw surfaces of various profiles, etc. are processed. Milling machines can be divided into the following main groups: general-purpose machines; specialized and special. The latter are designed to perform one or more specific milling operations on specific parts and are used in mass and large-scale production conditions. On general-purpose milling machines, blanks of parts of a wide range in individual and small-scale production are processed. Machines of that group include:

cantilever-milling;

nonsensical-milling;

longitudinal-milling;

carousel milling machines

A characteristic size of general purpose milling machines is the size of the working surface of the table.

Description of the machine

The vertical konsolnofrezerny machine of model 6P12 is intended for milling of various details from steel, cast iron and non-ferrous metals by face, trailer, cylindrical, radial and other mills.

Vertical, horizontal and inclined planes, slots, corners, frames, gears, etc. can be machined.

On the machine it is possible to process parts from light alloys. Technological capabilities of the machine can be expanded using a dividing head, a rotary round table and other devices. The machine is designed to perform various milling operations under conditions of individual and serial production. The technical characteristic and rigidity of the machine makes it possible to fully use the capabilities of a fast-cutting and hard-alloy tool. The ability to adjust the machine to various semi-automatic and automatic cycles allows you to organize multi-site service.

Feed Box

The feed box is provided by a flange motor mounted in the cantilever. By means of two three-wheel units and a movable gear wheel with a cam clutch, the feed box provides 18 different feeds, which are transmitted through a ball safety clutch to the cantilever and further when the corresponding cam clutch is turned on to the screws of longitudinal, transverse and vertical movements. Accelerated displacements are obtained by switching on the fast stroke friction clutch, rotation of which is carried out through intermediate gears directly from the feed motor. The friction clutch is locked with the working feed clutch, which eliminates the possibility of their simultaneous switching on.

Speed switching mechanism

The feed switching box flanked to the feed box body has a plastic limb at the front with a feed value and a switch fungus. The feed values indicated on the limb refer to the longitudinal and transverse feeds of the table. The feed box provides 18 feeds.

Forks of switchable gears are fixed on racks, the front part of which protrudes from the supply box housing and enters the switching box housing. Each rack has a paired, shorter rack connected to the first gear wheel. Axial movement of one rack causes the pair rack through the gear wheel to move in the opposite direction.

Axes of racks are located in two vertical planes, and axes of gears are reduced to one through hole. Group gears with mobile wheel units can transmit large torques and powers at relatively small radial dimensions.

Disadvantages of feed boxes with mobile wheels:

complexity of gearshift - for this it is necessary to turn off the drive of the feed box, slow down the shafts of the box until slow rotation, change the sliding wheel blocks, brake the drive and turn on the drive of the box, the possibility of accidents when changing mobile wheels on a fast run or while switching on two gears of the same group between adjacent shafts. Therefore, a lock that does not allow emergency actuations is required

relatively large axial dimensions of the group gear. The axial length of the group, where p is the number of gears in the group, b is the width of the toothed rim of the wheels of this group. To reduce axial dimensions it is accepted, where t - module.

Mobile wheel blocks are mounted on splined shafts, as a rule, spur wheels are used in them.

Adjustment of machine bearings

Adjustment of spindle bearings of rotary head:

To adjust the bearings, remove the plug on the front side of the swivel head. Move the sleeve and turn the spindle to install the nut with screw against the hole. Loosen the screw and, holding the nut, turn the spindle until you select the play in the bearings. When the required clearance is reached, tighten the screw and screw in the plug. Check bearing heating during operation at 1400 rpm. The heating temperature shall not exceed 700 C. In case of high heating, loosen the bearing tension with a nut.

Adjustment of spindle bearings of overhead head:

To adjust the bearings, remove the casing, move the tooth of the safety washer, wrench the nut until you select the play in the bearings so that the tooth of the safety washer coincides with the slot on the nut. Then tighten the tooth of safety washer into the nut slot and install the casing. Check bearing heating during operation at 1400 rpm. The heating temperature shall not exceed 700 C. In case of high heating, loosen the bearing tension with a nut.

Description of electrical circuit operation

The electrical equipment of the machine is designed to be supplied from a three-phase AC network with a voltage of 380V. and a frequency of 50 Hz. Control circuit voltages - 127V, local lighting voltage - 36V.

Electric circuit provides for :

zero protection of all motors;

protection of electric motors from short-circuit - by fuses, from long-term overloads - by thermal ones;

The electrical circuit allows to perform machining on the machine in the following modes:

Automatic Cycle (for longitudinal feeds only)

"Manual control, round table";

Selection of modes is performed by P.U. The supply motor is controlled from two command sets, for longitudinal supply - by one command set, for vertical and longitudinal supply - by two command sets.

Fast travel in automatic cycles is controlled by the limit switch.

The electric circuit also provides a limit switch, which eliminates the possibility of manual switching on of transverse and vertical feeds during operation in automatic cycles.

Lubrication of the machine

Lubrication of the feed box mechanism is performed by spraying of oil supplied by the tube from the cantilever. In addition, oil is supplied from the cantilever pump through a hole in the plane of connection of the supply box and the cantilever to the distributor of the supply box with three outlet tubes. Two tubes supply oil to needle bearings, and the third - to oil indicator, which controls oil supply to mechanisms of cantilever and supply box. The operation of the oil system is considered good if the oil at least partially fills the point of the oil indicator, this means that the oil comes abundantly and does not have time to flow out .

Industrial oil used in the lubrication system "ZO" (machine "L") GOST 170751 has viscosity in conditional degrees (Euler) at 500C (3.81... 4.59) cSt.

Before the initial start-up of the machine, it is necessary to:

fill the oil tanks in the bed, hobby, cantilever, and skids to the oil indicator hairlines with industrial oil "ZO" GOST 170751;

lubricant GOST 570365 using a syringe fill the holes for lubrication in the swivel head, in the housing of the cover head, as well as the hole in the trunk;

Lubricate the table mechanism and sled using a manual pump with industrial oil "ZO" (machine "L") GOST 170751, making 8 rocks of the plunger three times per tire.

During operation of the main motion and supply motors, oil must flow through the oil supply control indicators. In case the oil in the lubrication control indicator does not come on the machine.

Oil is sucked by speed box pump through strainer located inside bed. Before moving the table, skids and cantilever, their guides and the transverse feed screw must be lubricated from the manual oiler.

After three months after the machine is put into operation, it is recommended to change the oil in the tanks. To achieve the density of the junction of the supply box and the console, it is allowed to install it on paint or gas-thrust lubricant, if the gasket does not give sufficient oil permeability.

Conclusion

• Studied the characteristics and purpose of the machine;

• Conducted kinematic calculation;

• Selected an electric motor;

• Conducted verification calculations of shaft No. 5, gears and bearings on this shaft;

• Studied the principle of operation of controls;

• Studied the electrical circuit of the machine;