SURFACE GRINDERS: Reciprocating Table Type, Rotary Table Type, Vertical Spindle Type, Horizontal Spindle Type, Face Grinders, Way Grinders, Wet Belt Grinders

SURFACE GRINDERS

Surface grinders do almost the same operation as the planers, shapers or milling machines, but with more precision. Primarily they are intended to machine flat surfaces, although irregular, curved or tapered surfaces can also be ground on them. 

The common classification of surface grinders can be made as follows:

1. According to the table movement:

a) Reciprocating Table Type. 

b) Rotary Table Type

2. According to the direction of wheel spindles:

a) Vertical Spindle Type. 

b) Horizontal Spindle Type.

3. Special type and single purpose machines.

a) Face Grinders. 

b) Way Grinders. 

c) Wet Belt Grinders.

Reciprocating table type Surface Grinders:

A reciprocating table type surface grinder may have a horizontal spindle of the grinding wheel, or a vertical spindle of the same. The horizontal spindle carries a straight wheel and the vertical spindle a cup type wheel. Hydraulic drives are commonly used in all such grinders. Cutting is done on the periphery of the straight wheel, in case of horizontal type and on the revolving edge of the cup wheel on vertical spindle machines. The horizontal spindles are widely used in tool rooms. The work piece is held on a magnetic chuck on these machines. They are vastly used for grinding flat surfaces. The machine size is designated by the dimensions of the working area of the table.




Reciprocating table type Surface Grinders:


The longitudinal feed to the work is given by reciprocating the table. Forgiving cross feed, there are two methods. One is to mount the table on a saddle and give the cross feed by moving the saddle. Alternatively, the cross feed can be given by moving the wheel head in and out. In feed is provided by lowering the wheel head along the column.

In case of vertical spindle reciprocating table grinders the table along with work piece, reciprocates under the wheel. The wheel covers all or a major portion of the width of the job.

Cross feed to the work can be given by moving the saddle. A manual or power feed can be used to feed the wheel head vertically. An individual motor drive is provided to rotate the wheel.

Rotary table Surface Grinders:

Rotary table surface grinders are also made in two types. i.e. either having horizontal wheel spindle or a vertical wheel spindle.

A circular shaped magnetic chuck is mounted on the circular table to hold the jobs. The work pieces are normally arranged in a circle, concentric with the round chuck. If it is a single piece, it can be mounted centrally on the chuck. The table is made to rotate under the revolving wheel, both rotating in opposite directions.

Rotary table Surface Grinders




The vertical feed to the wheel is given by moving the wheel head along a column and the cross feed by the horizontal movement of the wheel spindle. A straight wheel is used on these machines, which cuts on its periphery. Some machines carry the provision to raise or lower the table also and also to incline the same.

A cup wheel has to be used on these machines. Vertical feed to the wheel is given by moving the wheel head. The work pieces are mounted on the round chuck in same way as in the horizontal spindle type. The table rotates in a direction opposite to that of the wheel and brings the work pieces one after the other under the rotating wheel. The table is mounted on a slide, so as to give cross feed. Some rotary table surface grinders are provided with two tables instead of one, so that, while the work pieces are being ground on one table, the other table can be used for loading the fresh batch of work pieces.

OTHER TYPES OF SURFACE GRINDERS

1. Face Grinder: 

It is similar in operation to a horizontal spindle reciprocating table surface grinder, but differs in that a vertical flat surface is ground instead of a horizontal one. The cutting is done on the face of the wheel and not on the periphery. Cup ring or segmental type wheels are used, which are mounted on a horizontal spindle and fed on to the vertical surface of the work piece, mounted on the reciprocating table. This type of the machine is used for large and heavy work pieces.

2. Way Grinder: 

It is a single purpose machine used for grinding the bed ways of different machines. It is a very large and heavy duty machine carrying a vertical spindle. Cup, ring or segmental type wheels are used on this machine. The wheel spindle can be tilted to a desired angle to grind inclined the work past the rotating wheel.

3. Wet Belt Grinders: 

These machines carry a vertical platen, which supports an endless abrasive belt revolving in a vertical direction. The table moves to feed the work against the belt and the table oscillates across the belt to effect desired grinding. The abrasive used on the belt carries the resinoid bond. This type of machine is specially used in grinding low fusion point materials as a large amount of heat generated is absorbed by the coolant, which is used in ample quantity.

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