Broaching


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Related to Broaching: Broaching Machine

quarrying

quarrying, open, or surface, excavation of rock used for various purposes, including construction, ornamentation, road building, and as an industrial raw material. Rock that has been quarried is commonly called stone. Quarrying methods depend chiefly on the desired size and shape of the stone and its physical characteristics. For industrial use (e.g., limestone for preparing cement), as the aggregate in concrete, or for road beds, the rock is shattered. Explosives are detonated in a series of holes drilled in the rock in a pattern designed to yield the greatest amount of fracturing. The rock fragments may be further reduced in crushing machines and sorted according to size by screening. For building stone, rocks that do not shatter are separated by blasting; for softer rocks or when explosives cannot be used (e.g., because they would disturb adjacent workings), a process known as broaching, or channeling, is used. In this process a line of holes is drilled perpendicular to the joints or cleavage planes of a formation; wedges are inserted into the holes and hammered until the stone splits off. This method was probably used in ancient times, notably by the Incas and the Egyptians. Much quarrying of ornamental stone today is done by using pneumatically operated channelers. After the vertical cuts have been made, gadding machines (working on the same principle) are used to make horizontal cuts. Wedges are then used to split off the long blocks, which are subdivided and removed. Wire saws are also used; these consist of several pulleys over which passes an endless steel wire. Holes are drilled in the rock, each hole being made large enough to accommodate a pulley and the shaft to which it is attached. The wire, extending from one pulley to another, presses down against the rock between them. As the cut is deepened by the constantly moving wire the pulleys are continuously lowered into the holes.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Broaching

 

a process of working metals by cutting on broaching machines using a tool with multiple blades called a broach. In light of the complexity and high cost of manufacturing broaches, the use of broaching is worthwhile for working large batches of parts, as in production of large lots or in mass production.

Types of broaching are distinguished on the basis of the order in which the final layer of stock is cut to size. In one method of cutting, all the broach’s cutting teeth remove the final layer, but they do not participate in the final shaping of the surface; this is done only by the last tooth. In a second method, each cutting tooth, in cutting the final layer of stock to size, simultaneously participates in forming the surface. A third method involves removing relatively large amounts of stock. In this method, all the teeth, which are arranged in groups of two or three, remove a layer of metal in sections rather than all at once across the entire width.

There are both free and coordinated methods of broaching. In the free method, the broach produces only the desired size and shape of the surface; in the coordinated method, the broach also produces the worked surface in the exact desired location relative to the reference surface.

In broaching, from 2 to 6 mm of stock is removed when working holes in forgings and castings. In holes produced by drilling, countersinking, countersink reaming, or boring, 0.2-0.5 mm of stock is left to be removed by broaching. The cutting speed in broaching is relatively low (2–15 m/min); efficiency is high, however, because the total length of the simultaneously cutting edges is great. Broaching produces a precision of class 3-2; the surface roughness of the worked surface varies from class 7 to class 9. A characteristic feature of broaching is the constant accumulation of chips in the depressions in front of each tooth. The teeth are often provided with grooves to break up the chips, thus improving the process of chip removal and preventing the broach from jamming.

REFERENCE

Vul’f, A. M. Rezanie metallov, 2nd ed. Leningrad, 1973.

N. A. SHCHEMELEV

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

broaching

[′brōch·iŋ]
(engineering)
The restoration of the diameter of a borehole by reaming.
The breaking down of the walls between two contiguous drill holes.
(mechanical engineering)
The machine-shaping of metal or plastic by pushing or pulling a broach across a surface or through an existing hole in a workpiece.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Broaching behavior refers to a consistent and ongoing attitude of openness with a genuine commitment by the counselor to continually invite the client to explore issues of diversity.
The tool cost of a dollar a part, plus the compressive stress put on the part by broaching, both were drivers, and both were negatively affecting the ability to get the transmission qualified.
Broaching competes favorably with other processes such as boring, milling, shaping and reaming.
For example both automotive OEMs and tiered suppliers seek integrated broaching solutions for which one manufacturer has the ability to supply a broaching machine, all necessary tooling, as well as service and support.
Those who have installed or considered installing a vertical broaching machine are sure to be familiar with the difficulties associated with its use.
Following this machining, various pieces of automation equipment deliver parts to a turn broaching cell consisting of two identical lines of three machines each.
Broaching continues to be one of the more effective metal removal processes being used today, especially in quality- and production-conscious applications, such as for automotive powertrain components, transmission gears, and shafts.