Boring Machine: Horizontal boring machine, Vertical boring machine, Precision boring machine, Jig boring machine ~ MECHTECH GURU

Boring Machine:-

· The boring machine is one of the most versatile machine tools used to bore holes in large and heavy parts such as engine frame, steam engine cylinders, machine housing, etc. which are practically impossible to hold and rotate in an engine lathe or a drilling machine.

· In addition to its primary purpose of boring the range of speeds and feeds provided to the various traversing components allow drilling, milling and facing to be performed with equal facility.

· By the fitting of simple attachments, the use of the machine can be extended still further to include screw cutting, turning, planetary or gear cutting.

Types of boring machine

· The boring machines may be classified under the four headings:

1. Horizontal boring machine

A. Table type

B. Floor type

C. Planer type

D. Multiple head type

2. Vertical boring machine

A. Vertical turret lathe

B. Standard vertical boring machine

3. Precision boring machine

4. Jig boring machine

A. Vertical milling machine type

B. Planer type

Horizontal boring machine:-

· In horizontal boring machine the work is supported on a table which is stationary and the tool revolves in a horizontal axis.

· A horizontal boring machine can perform operation like boring, reaming, turning, threading, facing, and grooving etc. with suitable tools.

· Workpiece which are heavy, irregular, unsymmetrical can be conveniently held and machined easily.

· Table type is the most common of all horizontal boring machines. In this boring machine work is mounted on the table.

· Table may be adjusted by hand or power in lengthwise or crosswise.

· The headstock may be adjusted vertically on the column.

· The machine essentially consists of a bed, headstock, supporting column, end supporting column, headstock, saddle and table, and boring bar.

· This machine is suitable for general purpose work where other operation, in addition to boring are required to be performed.

Horizontal boring Machine

1 – Headstock, 2 – Pulley for counter balancing weight of headstock, 3 – Headstock elevating screw, 4 – Boring head, 5 – Boring cutter on boring bar, 6 – Work, 7– End supporting column, 8 – Bearing block, 9 – Saddle, 10 – Cross slide, 11 – Table

Table type Horizontal boring Machine

1 – Column base, 2 – End supprting column, 3 – Table, 4 – Saddle, 5 – Spindle, 6 – Head stock supporting column, 7– Headstock, 8 – Motor,

9 – Bed

· Floor type horizontal boring machine having no table uses a stationary floor plate on which T - slots are provided to hold the work.

· The headstock supporting column and the end supporting column are mounted on the runways which are placed at right angles to the spindle axis.

· This is so designed for holding very large and heavy workpieces which are difficult to be mounted and adjusted on a table.

Floor type Horizontal boring Machine

1 – End supprting column, 2 –Column base, 3 – Spindle, 4 – Floor plate, 5 – Head stock supporting column, 6 – Head stock, 7– Motor

Floor type Horizontal boring Machine

· Planer type horizontal boring machine resembles the table type but table slides directly on the bed instead of on a saddle and reciprocates at right angles to the spindle similar to a planner.

· The end supporting column and headstock supporting column may be adjusted towards or away from the table for accommodating different width of the work.

· This type of machine is suitable for supporting a long work.

Planer type Horizontal boring Machine

1 – End supporting column, 2 – Column base, 3 – Table, 4 – Spindle, 5 – Headstock supporting column, 6 – Head stock, 7– Motor, 8 – Bed

· Multiple head type horizontal boring machine resembles a double housing planer or a plano - miller. The table is supported on a long bed on which it reciprocates.

· There are two vertical columns at two sides of the bed, nearly at the middle of the bed. The two columns are bridged by a cross rail.

· The machine may have two, three or four headstocks. This type of machine may be used both as a horizontal and vertical machine.

· The machining operations can be performed simultaneously at different work surfaces.

Multiple head type Horizontal boring Machine

1 – Cross rail, 2 – Headstock, 3 – Column, 4 – Headstock, 5 – Bed, 6 – Table

Vertical boring machine:-

· In this boring machine work piece rotate on a horizontal table and tool remains stationary except for the feed

Vertical boring Machine

1 – Feed adjusting levers, 2 – Tool box, 3 – Tool head assembly, 4 – Ram, 5 – Housing, 6 – Handwheel for ram adjustment, 7– Crossrail, 8 – Fine hand adjustmetn for ram,9 – Crossrail elevating screw, 10 – Table,

11 – Bed

· This specific design of the machine provides certain distinct advantages over a lathe for a particular class of work. The advantages are:

1. Large diameter and heavy workpieces, similar to chucking jobs on a lathe, may be set up more coveniently and quickly than on a lathe. It is easier to lay a workpiece down on the table rather than to hang it up.

2. The table and the work it carries rotate in a horizontal plane, and there is no overhang as in the case of a lathe spindle, and consequently any chance of bending the spindle which supports the heavy workpiece is eliminated.

3. The table being horizontal, the diameter of the table may be designed as large as possible to support large workpieces.

4. Multiple tooling may be adapted in the case a vertical boring machine with its turret type tool post increasing the rate of production.

· Vertical turret lathe combines the advantages of the vertical boring mill and the turret lathe. A vertical boring machine of smaller size is called a vertical turret lathe.

· It has an indexable turret mounted upon the cross rail above the table for multiple tooling.

Vertical turret lathe

1 – Housing, 2 – Crossrail, 3 – Saddle, 4 – Turret, 5 – Table, 6 – Bed

· A four station square turret side head which enables facing, turning, under cutting and many other operations is mounted at the side of the lathe.

· The cross rail may have vertical adjustments and for ease of operation it is counter balanced.

· The turret mounted on the saddle may be moved crosswise by hand or power. The turret may also be moved in a vertical plane. The side head also has up and down and to and fro adjustments from the center of the table.

· The machine is suitable for boring and turning railroad wheels, piston rings, gear blanks, etc.

· Standard vertical boring machine is larger in size than vertical turret lathe and there is no turret lathe.

· The machine is provided with two vertical heads and one or two side heads.

· The machine is particularly intended for boring large cylindrical and symmetrical workpiece.

· Turbine castings, locomotive tires, etc. are some of the common examples which need vertical boring machine.

Precision boring machine:-

· The precision boring machine uses single point tools to machine surfaces rapidly and accurately.

· Cemented carbide and diamond tipped single point tools are operated at a very high cutting speed to produce accurately sized holes with a fine surface finish.

· The feeding movement may be provided by the tool or by the work.

· The machine may be horizontal or vertical type.

Jig boring machine:-

· The jig boring machine is the most accurate of all machine tools. This was developed in the year 1910 in Switzerland and used as a locating machine. The real jig borer was first built in the year 1917 by Pratt and Whitney.

· The jig boring machines are now used for production of jigs, fixtures, tools and other precision parts which require high degree of accuracy.

· They characterized by provisions of highest accuracy through rigidity, low thermal expansion and precise spacing holes.

· The machining accuracy is very high, within range of 0.0025 mm.

· A jig boring machine resembles in appearance to a vertical milling machine, but so far its operation and accuracy are concerned there cannot be any comparison the two.

Jig boring Machine

1 – Spindle head, 2 – Quill, 3 – Column, 4 – Spindle housing, 5 – Spindle, 6 – Table, 7– Saddle, 8 – Bed

· The spindle and other parts of the machine are extremely rigid to resist deflection and the vibration is minimum.

· The spindle runs in preloaded antifriction bearing. The spindle housings are made of invar having a very low coefficient of linear expansion.

· The jig boring machine requires to be operated in temperature can be maintained constant. This is essential to prevent inaccuracy in the machine in the work being manufactured due to thermal expansion of the metal.

· Vertical milling machine type resembles in construction to a vertical milling machine.

· The spindle rotates on a vertical column and the horizontal table rests on the bed in front of the column.

· The positioning of the work mounted on the table may be obtained by compound movements of the table, perpendicular and parallel to the column face.

· Planer type consists of two vertical columns at the two sided of the table and is mounted on the base.

· The table has reciprocating movement for adjustment of the work. The spindle is mounted on the cross rail bridging the two vertical columns.

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· In a planer type jig borer, two co - ordinate movements for hole locations are provided by the longitudinal movement of the table and the cross movement of the spindle along the cross rail.