The Grinding Machine A grinding machine uses an abrasive wheel as a cutting tool to shape or change the dimensions of a hard material. The type of materials that need grinding are usually metallic items such as tools and rods. These machines generally work by reducing the material through abrasion. Grinding is used to finish workspaces that must show high surface quality and high accuracy of shape and dimension. There are several main parts in this machine. These parts are shown as below.
Picture Full machine Column Bed or base Tables Spindles Guide-waysTool post Control 2) Find the ribs and the reasons There are two types of ribs. These one are the longitudinal support ribs design. Stiffeners used in the arrangement provide significant movement in the bending and torsion’s stiffness of box-type structures.
The stiffeners of open structures, such as grinding beds, which consists of vertical shears connected by ribs also depends to a great extent upon the arrangement of stiffeners. The bending as well as the torque resistance of frame components may be improved by the provision of strengthening rib. ) Find the holes and gives the reason There are some holes in this machine tool.These holes provide their own function.
The picture below will explain about the function of every holes that exist in this grinding machine. Hole Reason The main purpose for this hole is to make the Joint or connection by using the screw. A hole is needs to transfer the flow of the liquid that use in this machine. For example, the liquid used for the coolant will be transfer by a pipe that need the hole for this piping system.
This machine required electricity as the main source energy. So, this hole is very important to create a hole for the installation of the wiring system.This hole is function as the flow of hot air. The heat is exposed during this machining, so the air flow out for the hot air is very important and can act as one of the cooling system. 4) Find all sideway for different movements and the force-flux between them and the MAT body a) For X-axis guide-way: Double eves type b) For y-axis guide-way: One flat and one eve type slide-way c) For z-axis guide-way: By referring to the machine manual the type of guide-way is double eves ) the force-flux between them and the MAT body is assumed as in figure below load is the effect of gravity on an object or structure.Meanwhile a dynamic load is the forces that move or change when acting on a structure.
What are static loads? Machining forces Weight of work Weight of machine components Source of static load: Friction loosen in sideway Friction losses in the feed of drive bearing Cutting force acting in feed direction of the table Source of dynamic load: Dynamic torque to accelerate the table, workplace, and lead screw assembly. It also plies in gears, motor and shaft.Changing in the depth of cut and stock removal Vibration because of intermittent cutting by multi edge cutters Heat sources in machine tool: Main heat source: Bearings Gear and hydraulic oil Drives and clutches Pumps and motors Sideways Cutting action and swear External heat source (environment) Friction in between tool and workplace: If the temperature generated by friction is high, the guides will undergo thermal deformation.To take out the heat generated, it is necessary to flood the guiding surface with lubrication oil ) Find the Joints and discuss about their rigidity In the grinding machine, there are 2 types of Joint are used which are bolt and nut and welding. Bolt and Nut Joint This type of Joint is a common temporary Joint that uses a bolt and screw to connect two parts. The size of the bolt is determined by the load required to ensure the rigidity of a machine. The bolt is inserted through a non-threaded hole and then a nut with washer is screwed on the other end of the bolt.
Welded Joint This type of Joint is a permanent Joint that connects two parts. Welded Joint is used n steel Joints where heavy loads are expected to put stress on the connection and does not allow for easy disassembly. Table below shows the Joint available in the machine that Joint between the parts. Joint between Type of Joint Picture Control and Bed Bed and Table Bolt and Nut Welding Column and Spindle Guide ways and Table Spindle and Tool Post The force in the bolted Joint tends to concentrate on the points where the two parts being held together by the bolts.
Meanwhile, the force in the welding Joint tends to concentrate on the line of the Joints. The concentration of the force on the contact areas causes a bending stress in the Joint. So, from the figure, we can see that the bolts are placed close as possible to the wall of contact in order to reduce the bending stresses.
There are other factors for the Joints to affect the rigidity of the machine. The factors are number of bolts in a Joint, size of a bolts, area of welding and types of welding. All of the factors depend on the load of the machine. The higher the load, the higher the number of bolts and welds area.From the figure, we can see that some Joints only use 2 bolts such as Joint between bed and table.
Some of the Joint use 4 bolts such as Joint between control and bed. This goes the same for the welding Joint where some Joint has high weld areas such as Joint between spindle and tool post. Some of the Joints only weld small area such as Joint between guide ways and table. To increase the rigidity of the machine, the critical area such as Joint between column and spindle has both bolts and welds.
This is because the parts receive high force during cutting process. So, the combination of both can increase the rigidity of the machine.