Types of Broaching Machines
Horizontal broaching machine
In this machine, the broach moves in a horizontal direction. A pull type broach is used. The pull type broach removes metal when it is pulled through the work piece. Internal and external broaching are done in this machine. But horizontal broaching machine is mainly used for internal broaching.
The machine has a base or bed. The base is of the box type construction. The length of the base is slightly more than the length of broaching stroke. The front of the machine has a vertical face. An adapter is fitted to this vertical face. The work piece is located in the adapter. The small end of the broach is inserted through the hole of the work piece. The small end is connected to the pulling head the other end of the broach is supported by the guide.
The pulling head pulls the broach. Normally the pulling head is driven by a hydraulic drive.
When the broach is pulled, it cuts the metal. After the cutting stroke, the pulling head returns back the original position. The broach end is separated from the pulling head. The machined work piece is un loaded.
Keyways, splines, slots, round holes and other internal contours are broached in this machine.
Vertical broaching machine
In a vertical broaching machine, the broach moves in a vertical direction. A push type broach is commonly used. The broach is fitted to a slide. The slide moves vertically along the guide ways of the column.
The movement of the slide is obtained through a hydraulic drive. The work piece is held in fixture. The fixture is clamped to the worktable. The left side view of the broach is shown in the figure. The broach does not have teeth throughout its entire width. The broach does not have teeth are made of three segments A,B and C. Teeth on the segment A cuts first on the central portion of the work piece. This method of broaching is known as progress broaching. If the width of the work piece is smaller, a single piece broach is sufficient.
Continuous broaching machines
Continuous broaching machines are used for mass production of small parts.
Horizontal continuous broaching machine
The machine has two rotating drums. They are connected by a endless chain. Drive is given to one drum. There are fixtures mounted on the endless chain throughout its length. The work pieces are loaded on the fixtures from one end. The broach is fitted horizontally in the frame of the machine. The work piece moves under the broach. The chain when it comes under broach slides over a rigid support. This gives rigid support to the work piece when broaching takes place. The work piece is unloaded at the other end.
Rotary continuous broaching machine
Small work pieces are fitted to a rotating table by the help of fixture. Broaches are fitted to a stationary broach holder which is placed at the center of the rotary table. There are three broaches. The table rotates continuously. The work piece moves past the broaches. The third broach is a finishing broach. The other broaches are for rough cutting. After the work pieces leave the finishing broach, they are unloaded. New work pieces are loaded to the fixture. Loading and unloading are done without stopping the rotary table.