NC Drilling and Milling Machine Design - Course

Contents

Entry

1 Comparative analysis of existing mill structures

2 General technical part

3 Design part

3.1 Kinematic calculation of the main engine drive

3.2 Approximate calculation

3.3 Calculation of gears per gearbox

3.4 Refined calculation of shaft for other

3.5 Calculation of bearings

3.6 Calculation of splined connections

3.7 Calculation of key connections

3.8 Kinematic calculation of longitudinal dachas

3.9 Kinematic calculation of axial dachas

3.9 Calculation of V-belt front

4 Description of design and operating principle of the designed equipment

4.1 Description of mill lubrication system

4.2 Description of Soon-to-Be Switching Mechanism

4.3 Description of the tool loading and fixing mechanism

4.4 Operating principle of the mill

Conclusion

Bibliographic Spy Juice

Appendix (Specifications)

Summary

NC Drilling and Milling Machine Design

The course design of MS 151001.2012.10.00.000.PZ, SZSU contains 2 li-hundred graphic parts of A1 format, 3 sheets of graphic parts of A2 format, 48 pages of explanatory note, 12 figures, 5 tables, 14 literary sources, 1 appendix.

In the course design, kinematic calculations of the speed box diagram were made; power calculations of the gearbox diagram, including approximate calculations of shafts for strength, calculations of gears for strength, updated calculations of shafts for strength; kinematic calculation of machine feed box.

In the graphic part of the course design, the following are developed: machine design, machine kinematic diagram, gearbox assembly drawing.

Introduction

The technical level of all branches of the national economy is largely determined by the level of development of mechanical engineering. Based on the development of mechanical engineering, complex mechanization and automation of production processes is carried out in industry, construction, agriculture, and transport.

In our time, machine builders are tasked with significantly improving the operational and quality indicators of products with a continuous increase in its output. One of the areas of solving this problem is improving the design training of students of higher technical educational institutions.

The implementation of the course project on "Metal Cutting Machines" continues the general technical cycle of training students. This is an independent creative engineering work, during which knowledge from a number of subjects passed is actively used: mechanics, material resistance, metal technology, machine parts, etc.

Software-controlled machines are increasingly being developed, including multi-purpose machines that provide high mobility of production, accuracy and processing performance. Automation is increasingly used not only to increase the performance of the processing process, but also to obtain its high quality indicators. Machine designs are subject to high requirements for quality, performance, reliability and safety in operation.

The object of the course design is to design a new NC coordinate boring machine. Coordinate boring machines are designed for processing holes with high accuracy of mutual arrangement relative to base surfaces in body parts, conductor plates, dies in single and small-scale production. On these machines, almost all operations characteristic of boring machines are performed. In addition, layout operations can be performed on coordinate boring machines. For accurate measurement of coordinate movements, the machines are equipped with various mechanical, optomechanical, inductive and electronic reference devices that allow measuring the movements of mobile units with high accuracy - 0,003... 0,005 mm. Machine tools are equipped with universal rotary tables allowing processing of holes in polar coordinate system and inclined holes.

General technical part.

On milling machines, flat and shaped surfaces are machined with the help of cutters, especially on levers, bars, body and other parts that are not bodies of rotation, local cuts and cuts are made, straight and screw grooves are cut, and in some cases threads and teeth of wheels are cut. The rotation of the cutter is the main movement, the relative movement of the cutter and the workpiece (usually rectilinear) is the feed movement. Behind the cooking is installed on the table, almost always rectangular. The dimensions of the working surface of the table are basic. In this course design, it is necessary to ensure the size of the table width (Bst = 350 mm).

Milling machines are classified by layout (number and distribution of spindles, distribution of movements) or by purpose: horizontal milling cantilever machines, vertical milling, longitudinal milling, copying milling machines, continuous milling machines, including carousel milling machines, etc.

Vertical milling machines have the greatest capabilities.

The deviation of the roundness of the holes obtained by milling using NC systems is about 30 mm.

With the use of additional replaceable units (milling heads, faceplates, etc.), it is possible to mill mutually perpendicular planes, stretch grooves during radial movement of the faceplate slider installed in the spindle, and process external cylindrical surfaces.

Modern machines have an individual feed drive from high-torque engines for each axle. The operating feed reaches 12,000 mm/min and the accelerated feed reaches 15,000 mm/min. Contour control with the number of axes from 3 to 8 is used. The accuracy of the linear positioning of the nodes is about 15... 30 μm at a length of 1 m. The insensitivity zone is about 5 μm, and the repeatability is about 10 μm.

During the course design, you must design a drill and milling tool based on a NC vertical milling tool to meet the requirements specified in the job.

4.3 Description of tool loading and fixing mechanism.

The workpieces on the designed machine are processed sequentially by several cutting tools, so there is a specialized tool changer on the machine, carrying up to 18 tools.

In the designed machine, the tool fixed in the mandrels is located in the tool magazine, from which it is removed by means of a rotary manipulative grip and inserted into the spindle. With the same grip, the tool used is removed from the spindle. Mandrel is secured with tool in spindle by ball clamp driven by hydraulic drive. The NC device coordinates the operation of the clamping and changing hydraulic drive and the installation of the tool by the manipulator.

The process of using cutting tools on CNC machines involves two main steps:

assembly and assembly of cutting tools taken in stock by means of their installation in shanks and mandrels; their subsequent dimensional adjustment on special instruments within the framework of developed unified tool systems (respectively for NC milling and multi-purpose machines); storage of assembled and tuned tool blocks, selection of the necessary set of assembled and tuned tool in the warehouse, its installation in the tool magazine on the machine; sequential selection of the required tool in the process of processing the workpiece, its automatic change with installation and fixation on the working tool of the machine; release, remove and return the tool to the magazine; return the tool after processing a batch of blanks to the warehouse, and if necessary, disassemble it for repeated sharpening or replacement.

4.4 Principle of machine operation.

A drilling and milling machine based on a NC vertical milling machine, unlike similar hand-operated machines, is equipped with cross tables that automatically move the machined workpiece along the coordinate axes x, y, z, as a result of which there is no need for conductors or for preliminary marking of parts. Vertical supply is carried out by the console.

The designed machine is equipped with a ten-position turret (magazine) switchable by the control program and an automatic tool change mechanism.

The main components of the designed machine are specified in the drawing MS 151001.65.2012.10.00.000 SCh. A column is installed on the base, along the straight-coal guides of which the cantilever moves. Speed gearbox is mounted in the column. Horizontal and vertical displacement feed drives are arranged in cantilever. Machine has suspended control panel.

Main machine units (see drawing MS 151001.2012.10.00.000.SB "Drilling and milling machine with NC Assembly drawing"): 1 - frame, 2 - sled, 3 - table, 4 - tool magazine, 5 - rack, 6 - CNC console, 10 - speed box.

Conclusion

As a result of this course project, a drilling and milling machine with numerical software control was designed. Including, kinematic calculations were made of two speed box schemes; power calculations of the selected gearbox scheme, including approximate calculations of shafts for strength, calculations of gears for strength, updated calculations of shafts for strength, calculations of bearings of gears and shaft supports, calculation of key connections, as a result of which the most rational kinematic scheme of the gearbox was chosen, which was used in this machine; and kinematic calculation of the machine feed box was also carried out, lubrication and cooling systems of the machine were developed.

The designed coordinate boring machine with numerical program control has a number of advantages compared to the currently mass-produced coordinate boring machines (see para. 1). This machine is competitive at this time and will undoubtedly find its application in the engineering industry, and, therefore, its design is economically justified.

The implementation of this course project is inextricably linked with the use of computers. In particular, a set of automated Compass 13 systems was used to execute the graphic part of the project, and a Microsoft ® Word ® text editor was used to design the explanatory note.