In this article, you’ll learn about horizontal boring machine its parts, types, tools and operations.
Horizontal Boring Machine
The boring machine is one of the most versatile machine tools is using to bore holes in large and heavy parts such as engine frames, steam engine cylinders, machine housing, etc.
Which are practically impossible to hold and rotate in an engine lathe or in a drill machine. The boring machine has, therefore, been developing primarily to do this. So in this article, we will discuss all the information about the horizontal boring machine.
In addition to its primary purpose of boring, the range of speeds and feeds providing to the various traversing parts allow drilling, milling and facing to perform with equal facility.
By the fitting of simple attachments, the use of the machine can extend still further to include screw cutting, turning, planetary grinding, or gear cutting.
In types of boring machine, the horizontal boring machine is one of the most useful and important machines. Let’s see how it works.
Horizontal Boring Machine Parts
In a horizontal boring machine, the work is supporting on a table which is constant and the tool turns into a horizontal axis. A horizontal boring machine can perform boring, reaming, turning, threading, facing, milling, grooving, recessing and many other operations with suitable tools.
Workpieces which are heavy, irregular and off-balance can conveniently hold and easy to machining. Different types of horizontal boring machines design to suit different purposes.
Following are the main parts of horizontal boring machine:
- Headstock supporting column
- End supporting column
- Saddle and table
- Boring bars
- The bed is that part of the machine which is fitting on the floor of the shop and has a box-like casting.
- The bed supports the column, tables and other parts of the machine.
2. Headstock Supporting Column
- The column provides support to the headstock and guides it up and down accurately by the guideways.
- The column which has hollow houses and is heavily ribbed to add rigidity.
- Some columns are stationary, others may be made to slide along the bed.
3. End Supporting Column
- The end supporting column situated at the other end of the bed houses.
- Bearing block is provided for supporting a long boring bar.
- The column may be adjusted on the slideways of the bed towards or away from the spindle for supporting the different length of boring bars.
- It may be moved at right angles to the spindle as in the case of a floor type machine.
- The headstock mounting on the column supports, drives, and feeds the tool.
- A spindle provides rotary movement to the tool and the quill may be moved longitudinally to provide feeding movement of the boring cutter.
- The spindle nose is provided with a tapered hole for receiving taper shanks of the boring bar or any other tool.
- A headstock may move up and down on the column for setting the tool for different heights of the work.
5. Saddle and Table
- The tables support the work and is, therefore, provides T-slots for holding various devices.
- The saddle allows the work to be moved longitudinally on the bed. The table may be moved crosswise on the saddle.
- These movements may be slow or rapid and are performed by hand or power.
6. Boring Bars
- The boring bar supports the cutter for holding operations on jobs having large bore diameters.
- For short holes, the bar may support on the headstock spindle end only.
- For long work, the bar is supported on the spindle end and on the column bearing block.
Types of Horizontal Boring Machine
The following are the four types of horizontal boring machine:
- Table type horizontal boring machine.
- Floor type horizontal boring machine.
- Planner type horizontal boring machine.
- Multiple heads type horizontal boring machine.
1. Table Type Horizontal Boring Machine
The table types are the most common of all horizontal boring machines.
The name horizontal boring machine is given because the work is mounting on the table which is adjustable and feeds is giving by hand or power, lengthwise or crosswise with respect to the bed of the machine.
The headstock may adjust vertically on the column and the spindle has a horizontal feed motion.
The machine essentially consists of a bed, headstock supporting column, end supporting column, headstock, saddle and table, and boring bar. The table, saddle and headstock may adjust by leadscrews using micrometre dials.
This type of machine is suitable for general purpose work where other operations, in addition to boring, is required to be performed.
2. Floor Type Horizontal Boring Machine
The floor type horizontal boring machine having notable uses a constant floor-plate on which T-slots is providing to hold the work.
The headstock supporting column and the end supporting column is mounting on the runways which are placed at right angles to the spindle axis.
Thus any crosswise adjustment or cross-feed movement is providing by the spindle itself and not by the work.
This is so designed for holding very large and heavy workpieces which are difficult to be mounted and adjusted on a table.
3. Planer Type Horizontal Boring Machine
The planer type horizontal boring machine resembles the table type but the table slides direct on the bed instead of on a saddle angles to the spindle similar to a planer.
The end of the supporting column and headstock supporting column may adjust towards or away from the table for accommodating different widths of works.
This type of machine is suitable for supporting a long work.
4. Multiple Head Type Horizontal Boring Machine
The machine resembles a double housing planer or a Plano-miller. The table is supporting 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 use as a horizontal and vertical machine.
The machining operations can perform simultaneously at different work surfaces.
Size Of A Horizontal Boring Machine
The size of a horizontal boring machine is specified by the diameter of its spindle in mm. The diameter of the spindle varies from 75 to 355 mm.
To specify a boring machine fully other important dimensions such as spindle motor horsepower, column heights, size of the table or size of the floor plate, spindle speeds, feeds and length of feeds, floor space requires, the weight of the machine, etc. should also be stated.
Boring Machine Mechanism
The machine contains different controls for movements of the different parts of the machine. A table type machine has the following movements:
- The headstock and the end supporting block may be moved up and down.
- The spindle may be rotating. The spindle has different speeds.
- A spindle may move in or out by hand or power for feeding.
- The saddle and the table may move by hand or power.
- The columns may move by hand or power.
All these movements may be given independently or in combination with two or more movements.
As all the controls are housed in a particular position of the machine the operator may give close attention to the work while controlling the machine.
Work Holding Devices For Horizontal Boring
The work may be supported on the table by the conventional work holding devices or by special fixtures.
Conventional work holding devices comprise T-bolts and clamps, angle plates, step blocks, etc. Special jigs are used in mass production work.
The jigs are locating the work and support and guide the boring bar.
Horizontal Boring Machine Operations
In boring, the work remains stationary and the tool is rotated. Holes are bored by using boring bars.
Multiple holes are bored one after another by changing the position of the workpiece aligning it each time with the boring bar.
To bore a hole, the boring bar is fitted to the spindle and the cutter is adjusting in the boring bar to the required dimension and a light cut is then taken.
The bore is measured, required speed and feeds adjusting and the cut is then completed.
In a boring machine, for milling operation, any type of milling cutter may fit the spindle. Facing cutter is using for machining flat vertical surfaces.
For face milling operation, the tool or work may be fed to complete the cut. The end mill is using to produce grooves and slots. Is illustrates in face milling operation.
All other operations such as drilling reaming, counterboring, tapping and spotfacing operations may perform similarly to boring operations. Is illustrating in the drilling operation.
Boring Tool Mountings For Horizontal Boring
The different types of equipment for mounting cutters ina horizontal boring machine are:
- Boring bar
- Boring head or cutter head
- Facing head
1. Boring bar
Ordinary boring operations are carried out with tools mounted on a bar held in spindle having morse taper hole.
The maximum diameter of the bar employed is ordinarily not larger than the spindle diameter, and the length is such that it can reach the end column support.
A boring bar should be of the maximum diameter and minimum length to reduce bending or vibration and it may support in various ways to suit to different types of workpieces.
1.1 Methods of Supporting Boring Bars.
Supporting by Spindle
For boring blind holes, bars are using to support at the spindle end only. This type of bar is known as a stud bar.
Supported by the spindle and end column
While boring long open holes, boring bars are supported at the spindle end and by a bearing block at the other end mounted on the end supporting column.
This type of bar is called a line bar. It illustrates a line bar.
Supported by the workpiece
In some types of work, the bar may be supported in the bored holes of the work by bushings.
This type of support takes much of setting time and is using in stray jobs where only one or two similar articles are machined that do not call for a special jig to be manufactured.
Supported by boring fixture
boring jigs are mainly using in mass production work.
They locate, guide and support the bars at intermediate points. It illustrates a boring bar which is supported by a boring fixture.
Boring bars are using for boring smaller diameter holes are made of manganese-chrome alloy steel annealed to relieve internal stress.
Heat treated bars of medium carbon steel alloyed with chromium and manganese are using where the severe cutting condition exists.
Methods of attaching cutters on boring bars
There are various methods of attaching cutters to boring bars. Slots are cut at intervals along the entire length of the bar so that the cutter may be set at the required position.
Different types of a cutter are using for different classes of work. The most important type of cutter is a fly cutter.
It consists of a single point cutting tool is mounting on a bar. The adjustment of the fil cutter may be made by a micrometre dial.
Double cutters are wide to a great in production boring as the machining time is reducing to a great extent compared to that of a single point fly cutter.
1. Boring Head or Cutter Head
The boring head is using for mounting cutters while machining large diameter holes where a standard boring bar is unsuitable due to the smaller diameter or excessive overhang of the cutter.
Boring heads having the maximum permissible diameter.
This device amply supports the tool and reduces machining time due to the larger number of cutting edges.
The cutters may adjust by micrometre dials. it illustrates in the boring head.
2. Facing head
The facing head is mounting on the end of the spindle. It comprises a flange provides with a diameter slide-way on which the tool carrying a bracket may be adjusted.
The bracket may be fed radially or located and clamped at the centre for supporting a long boring bar.
A facing head enables enlarging of large diameter holes, facing an external turning operation. it is illustrating in the facing head.
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