calculation of vertical milling machine speed box

Introduction

Course work in the discipline "Metal Cutting Machines" is an important link in the training of a mechanical engineer. This is a complex creative work in which a student must show the ability to apply both previously acquired knowledge in general engineering and special disciplines and knowledge in this discipline when solving practical problems.

Course work sets its task to teach the student to independently understand technological, kinematic, structural and economic issues of designing metal cutting equipment.

In most cases, the main part of the course work is the development of drives of the main movement or feed movement. At the same time, the student should not be limited to solving the issues of only the designed node. It is necessary to critically understand and clearly know a number of general issues related to the entire machine, its technological purpose, compliance with the modern level of performance, accuracy, automation, requirements of technical aesthetics, safety, etc. During the course project, the student must learn to apply standards, normals, typical diagrams and designs, reference technical literature.

Given the importance of coursework in the preparation of a student, it is credited in the form of a public defense against a commission consisting of at least two teachers. Only those course works in which all sheets of the graphic part and the calculation and explanatory note are viewed and signed by the project manager are allowed for protection. A manager's involvement in protection is not necessary.

The student should prepare a report highlighting the tasks and main content of the project, specific decisions made on all parts of the work with the necessary justification, emphasizing new solutions in the work. In the course of the report, the student must highlight the contents of all sheets of the graphic part of the project. The length of the report is not more than 810 minutes.

After the report, the members of the commission ask questions, both on the content of coursework and in order to test general technical and special knowledge.

Selection of analogue machine

As a prototype machine, according to the task, we accept machine 6P12.

The 6P12 vertical milling machine has high technical and operational characteristics. This equipment is used to process various billets made of steel, cast iron, non-ferrous alloys. The device works equally efficiently with simple and complex parts. The main operation is mainly performed on the end and end cutters.

The drive power and high rigidity of the machines allow the use of fast-cutting steel mills, as well as tools equipped with plates made of hard and super-hard synthetic materials.

Design Features:

mechanized attachment of the tool in the spindle;

proportional mechanism of supply deceleration;

device for periodic adjustment of clearance in helical pair of longitudinal supply;

safety clutch to protect the feed drive from overloads;

braking of horizontal spindle at stop by electromagnetic clutch;

device for protection against flying microcircuits.

Process:

various automatic operating cycles;

wide range of spindle speeds and table feeding;

high-power drives;

high rigidity;

reliability and durability.

Automation of machine operation

To facilitate the maintenance of the milling machine when changing the tool, we use the automatic tool change method.

Tool change mechanism is made separate unit and consists of automatic operator, gearbox, reloader, handle, sleeve, control mechanism and drum-type tool magazine with capacity of 12 tools.

The tool is selected in any sequence.

The operator delivers from the magazine to the spindle and returns the used tool from the spindle to the magazine.

In the process of replacing the tool, the auto operator provides its deviation outside the working zone of the machine, which helps to reduce the maximum working space and eliminates the possibility of chip ingress on the working surfaces of the tool holders.

The entire tool change mechanism is located in an area convenient for servicing the machine.

The magazine is a case mounted on a special rack, standing separately from the car. In the housing there is a motor rotation magazine, which rotates the drum with the help of a tool.

The drum is a large diameter disk, on the periphery of which there are grooves for the tool. When the command is received, the drum begins to rotate, the search for the necessary tool is carried out by the rotating transformer. When approaching the specified position of the tool, the drum decreases speed and then stops. After that, the loader begins to work. It transfers the sleeve from the tool from the magazine socket to the operator's hand and vice versa.

Reloader is a reduction gear, on speed shaft of which ticks are fixed. Ticks are open in the store.

When moving to the car operator under the influence of Belleville springs, the pliers clamp the clutch and transfer it to the car tool.

The operator is equipped with a two-hand lever that directly grabs the tool in the sleeve and spindle and changes them. At the same time, the new tool is installed in the spindle, and the used tool is installed in the sleeve.

The tool is changed first by axial movement of the hand from the spindle, turning it 180 °, and then by reverse axial movement to the spindle.

The amount of axial displacement is calculated so that the tool completely leaves the spindle and sleeve, and in the opposite direction it is fully fixed in its place in the spindle and sleeve.

Axial movement of the hand is carried out when the machine operator moves the carriage from the crank mechanism. The turn of the hand is carried out by the Maltese mechanism. After installation of the tool in the appropriate seat of the drum, the loader ticks open under a rigid stop, the drum begins to rotate, and the tool necessary for the next operation is installed on the loader.

The loader takes it and carries it to the car operator. The tool changes after the previous operation. Thus, all preparation for the tool change takes place during the operation of the machine, which significantly reduces the time of the shift itself.

Conclusion

During this course work, the goal was achieved, namely, the calculation of the kinematics of the high-speed box of a vertical milling machine.

The developed gearbox of this machine meets all safety requirements during the operation of the machine, its maintenance and repair.

The range of rotation speeds of the main motion drive corresponds to this type of machine, as well as a given structural formula.

The drive power of the main movement is designed so that it provides the necessary cutting conditions and methods for processing parts at all speeds of the spindle.

Calculation of rotation speed charts is carried out strictly in accordance with the task, taking into account all the recommendations set out in the manuals and manuals.

The determination of gear ratios and the number of gear teeth is calculated in accordance with the current standards in machines.

The speed of peripheral engagement of the wheels does not exceed the permissible value for the selected type of cylindrical gears.

An analytical check of the accuracy of kinematic calculation shows that the calculated actual speeds are within acceptable limits of normal speeds.

The power calculations of the gears of the designed gearbox satisfy the design conditions of endurance of the teeth surfaces during bending and contact endurance conditions for this type of gears.

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