Reporte de práctica - maquinado y ensamble

[pic 1]

Objetives

1. Knowing and making correct use of the main machines of a workshop (lathe, milling machine, cutting machine, etc) by performing one piece machining during 6  class sessions.

1. Make correct reading of engineering drawings and make the machining of a piece from the reading of the engineering drawing.

1. Finish the 7 pieces in 6 sessions to make an assembly based on engineering drawings.

Material and/or equipment

• Material and/or equipment for piece and assembly:

• Steel 1018 (Base)
• Steel 1020 (Bushing plate, central post, open round, spike, bearing)
• Steel 1095 (Knurled screw)
• Bronze (Guide bushing)

• Material and/or equipment for piece machining (bearing):

• Conventional lathe
• Milling machine
• Chuck key
• Turret key
• Metal shims
• Cutter for lathe
• Dial indicator
• Revolving drive centre
• Bur-guards 
• Center drill bit 1/2’’
• Vernier
• Bronze hammer
• Drill 5/8”
• Drill ¼”

• Safety equipment and equipment:

• Safety boots
• Safety glasses
• Workshop coat

Method

To machine the piece 7 (bearing) two machines were used:

• Conventional Lathe:  

A lathe is a set of machines and tools that allow machining, threading, cutting, trapezing, drilling, rolling, grinding and grooving pieces of geometric shape per revolution. These machine tools operate by rotating the piece to be machined (held in the head or also called chuck fixed between the centering points) while one or more cutting tools are pushed in a regulated movement of advance against the surface of the piece, cutting the chip according to the appropriate technological machining conditions.

Starting from a piece called "base", parts with the blade to the base piece are eliminated until leaving it with the shape that we want. The main movement in the turning is the rotation and is carried by the piece to which we are going to give shape. The movements of advance of the blade and of penetration (put the blade on the piece to cut it) are generally rectilinear and are the movements that the cutting tool carries.
For this process you must first fix the base material to the lathe chuck. The lathe is turned on and the mandrel is turned. It moves the cars where the blade is to the base material. With the auxiliary carriage the blade moves to make the desired shape on the base part.
The speed at which the workpiece rotates in the lathe is an important factor and can influence the production volume and the duration of the cutting tool.
A very low speed in the lathe will cause losses of time; a very high speed will make the tool dull very soon and you will lose time to sharpen it again. Therefore, the correct speed and feed are important depending on the material of the piece and the type of cutting tool used.

• Milling machine:

A milling machine is a machine tool for machining operations by chip removal by the movement of a rotary tool with several cutting edges called a milling cutter. Through the milling can be machined the most diverse materials, such as wood, steel, cast iron, non-ferrous metals and synthetic materials, flat or curved surfaces, notches, grooves, teeth, etc. In addition, the milled pieces can be trimmed or tuned.

Using a milling machine requires a series of unavoidable steps. First of all, the piece to be worked must be fixed and, to prevent it from moving or vibrating, you have to choose the right cutter for the job you want to do.
Then, the milling cutter is clamped firmly on the router clamp, the maximum milling depth is adjusted according to the type of cut and, finally, the workpiece is blocked.
Before starting the engine, the machine must be held firmly in both hands. Then it is placed on the surface to be worked, the engine is started and introduced progressively on it in the opposite direction to the movement of the milling cutter. The movement of the machine should be slow and regular. If the cut is deep, it should not be done all at once. For an optimal result, several passes are necessary.

In addition to the individual machining of each piece, an assembly of all the pieces will be made. In an assembly, two or more parts are joined to form a new entity. There are permanent, semi-permanent and non-permanent assemblies.

To make a non-permanent assembly usually threaded fasteners are used, these represent the most important category of the mechanical assembly. They are all those separate components of the equipment that have external or internal threads for the assembly of parts. They generally allow disassembly.

...