Lathe Design

Contents

Introduction

1. General technical part

2. Comparative analysis of existing structures

2.1. Product Competitiveness Assessment Philosophy

2.2. Product Competitiveness Analysis

2.3. Calculation of integral competitiveness index of the designed machine

2.4. Machine Data Sheet

3. Description of machine design and operation

4. Kinematic calculation of the main motion drive

5. Kinematic calculation of feed drive

6. Approximate Shaft Calculation

7. Gearbox Strength Calculation

9. Bearing calculation

10. Calculation of key connections

11. Calculation of belt transmission

12. Description of speed switching mechanism

13. Description of the mechanism for loading and fixing blanks

14. Description of tool loading and fixing mechanism

15. Lubrication system

Conclusion

Bibliographic list

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 in industry is carried out.

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.

All the information necessary for the course work is taken from various technical literature given in the bibliographic list.

Design recommendations and individual design solutions take into account the modern level of both domestic and foreign engineering.

During the course design, we pass sequentially from the selection of the cutting scheme through the multivariability of the solution to the creation of a new metal cutting machine in the working drawings; getting involved in engineering creativity, learning from previous experience, learns to find and anticipate new ideas in creating a tool that is reliable and durable, economically profitable in manufacture and operation, convenient and safe to maintain.

1. General technical part.

In CNC machines, the part processing cycle is fully automated with the establishment of the necessary cutting modes, as well as all auxiliary movements and functions: accelerated movement of working elements, change of the tool installed in turret heads or magazines, clamping of the workpiece, movement of the tailstock and lunette, switching on and off of chip removal mechanisms, cooling systems, introduction of correction to the position of tools pre-tuned to size.

Modern CNC lathes have an original layout that allows increasing their rigidity, improving the protection of guides and screw gears, ensuring the free removal of chips and their removal from the working area, using loading devices of any type, providing free access to the tool and devices, and improving work safety.

The machine can be used in small-scale production, in small enterprises, in repair shops.

3. Description of machine design and operation

CNC lathes are designed for high-performance processing in automatic mode of workpieces such as bodies of revolution in conditions of small-scale and mass production.

In CNC machines, the part processing cycle is fully automated with the establishment of the necessary cutting modes, as well as all auxiliary movements and functions: accelerated movement of working elements, change of the tool installed in turret heads or magazines, clamping of the workpiece, movement of the tailstock and lunette, switching on and off of the chipbreaking and chipbreaking mechanisms, switching on the cooling system, introduction of correction to the position of tools pre-tuned for size.

Modern medium-sized machines have, as a rule, an original arrangement that allows increasing their rigidity, improving the protection of guides and screw gears, ensuring the free removal of chips and their removal from the working zone, using loading devices of any type, providing free access to tools and devices, and improving work safety.

Variable DC and AC motors are commonly used as drive motors in CNC machines. The latter are simpler and have more reliability in view of the lack of brush units. The constant-power engine control diopason is limited to 6... 8.

In most cases, modern machines use reducing-free feed tracking drives with high-torque adjustable motors and feedback sensors built into the engine or connected by a non-locking clutch with a drive screw.

12. Description of speed switching mechanism

Speed boxes are structurally included in the drive of stepped control of the main movement of the machine. The machine drive is a combination of an energy source (electro, hydraulic or pneumatic motor) and transmitting devices; its purpose is to drive the machine tools carrying the workpiece or tool, while providing the necessary speeds and transmitting the required forces.

Speed boxes provide:

• large range D of speed control at output: D - wmax/wmin- Here "max and" min, respectively, the maximum and minimum speed (min-1) of the spindle, with straight main movement - the maximum and minimum number of double strokes per minute of the slider or table;

• no slippage (constant gear ratio);

• transmission of constant power;

• a sufficiently large number of different exit speeds at relatively small dimensions of the speed boxes themselves;

• transmission of high torques;

• high efficiency

Speed boxes are compact, easy to maintain and reliable to operate. The gearboxes of the machine consist of two-shaft gears, which can transmit several different speeds to the driven shaft II. The transmission with the movable gear block is simple in design, but does not allow switching on the go. Transmission with a clutch makes it possible to automate speed switching without stopping the rotation of the driving shaft I. Automatic speed boxes (ACS) are used in automated machines, in which speed switching is carried out using electromagnetic friction clutches.

13. Description of the mechanism for loading and fixing blanks

The issues of fixing the workpieces on metal cutting machines, ensuring the reliability of their supply to the processing, transportation and accumulation zone should be resolved in a comprehensive manner, taking into account the peculiarities of processing, the capabilities of the machine and the requirements for processing accuracy. The main requirements are reliability of basing while maintaining the required stiffness of the part, increasing equipment productivity, reducing maintenance personnel and improving working conditions.

Various machine tool systems are provided, classified according to the degree of specialization, readjustability, availability of standard elements and their use in various devices, etc.

Devices for fixing workpieces are designed for machine tools of certain groups. In turning and grinding machines, front and rear centers, driving devices, lunettes, mandrels, cartridges and faceplates are widely used. Special fixture designs allow complex reciprocal movements of the workpiece and tool.

Hydraulic actuators of clamping devices allow the use of a higher pressure than the pneumatic drive. This makes it possible to obtain significantly higher forces while reducing the overall dimensions of the working cylinders. The hydraulic drive is characterized by silent operation, reliable lubrication of friction parts, structural simplicity of mechanisms with multipoint fixation .

Hydraulic pumps, pneumatic hydraulic transducers, accumulators of various types can be used as a source of liquid supply. To control the output links of the clamping mechanism, one-way hydraulic motors with reciprocating and rotating motion of the working member are most often used.

14. Description of tool loading and fixing mechanism

Machining of workpieces on metal-cutting machines is usually carried out sequentially by several cutting tools and therefore requires the presence on the machine of an appropriate set of assembled and tuned in special shanks and holders of the cutting tool, as well as its sequential use on the machine.

The installation of cutting tools on the workpiece of the machine (spindle or caliper), their fixing, as well as removal, of the used tool, can be carried out manually or automatically.

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 holders; their subsequent dimensional adjustment on special devices within the framework of developed unified tool systems (respectively for NC turning and multi-purpose machines); storage of assembled and configured tool blocks;

selection of the necessary set of assembled and adjusted tools 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.

Sequential selection of the required tool in the machine tool magazine, its automatic installation and fixation on the machine tool, subsequent return of the tool to the magazine is carried out by the automatic tool change system.

The ISI includes:

tool magazine for accumulation of tools (on CNC lathes, 1,2 or 3 turret heads);

an auto operator for changing a tool;

clamping mechanism of shank or cutter holder with tool on working tool of machine.

Modern CNC lathes in most cases have a turret head (one, two or three) in the positions of which different cutting tools are installed. Their installation is also carried out using an auxiliary tool.

Currently, two auxiliary tool subsystems have been developed for CNC lathes: with a cylindrical shank and a base prism.

15. Lubrication system

The operation of the machine largely depends on the quality of lubrication of various units and parts. During operation of the machine, all parts of the headstock from the automatically operating plunger pump.

The plunger pump supplies oil from the tank, through plate filters to the front support, from there it is sprayed and spread over the rubbing pairs, providing good lubrication.

Cuff seals and rubber gaskets are used to prevent oil from flowing out of bearing assemblies, as well as to protect them from dust and moisture.

Screws of transverse and longitudinal feeding of the machine and their guides are lubricated with presses.

Industrial oil AND 30A GOST 2019975 was widely used for lubrication.

Lubrication system used in the machine - circulation

Conclusion.

During this course project, a lathe with the specified parameters was designed. During the operation, the speed box (for which kinematic calculation was carried out) and the machine feed box were designed, as well as the necessary check calculations were performed, namely, the check calculation of bearings and key connection.

During the course project, the competitiveness of the designed lathe was calculated using the integral indicators method, for which the main technical indicators of the designed lathe were compared with the competitor machines. The comparison showed that the designed machine has quite high technical characteristics, which makes it quite competitive, which was proved by calculations.

Therefore, a lathe with specified parameters is designed in the course design