Stirrup machine

A stirrup machine for bending metallic stock material such as bars, wire, strips and the like and forming individual bent pieces therefrom including: advancing and reversing and other suitable apparatus (1) for selectively advancing and reversing the feed of the stock material (2) and to retract the finished bent product; shear and guide apparatus (3) for the stock material (2); bending apparatus (4) having an interchangeable fixed central bending fork (7) to guide and support the stock material (2) and a bending pin (8) for bending the stock material (2) around the central fork (7) in a clockwise or counterclockwise direction. The invention is characterized in that the stock guide apparatus (5) is tranversally movable forward and backward to push the stock material (2) out of the bending plane, to disengage it from the bending apparatus (4) or to recall the stock material to re-engage it with the respective bending apparatus (4) and to shear it in connection with a countershear (6) after the stock material (2) has completed a stirrup.

FIELD OF THE INVENTION 
This invention is related to a stirrup machine or a bending machine for 
metallic stock material such as bars, wire, strips or the like. 
BACKGROUND OF THE INVENTION 
Semi-automatic or automatic stirrup machines or bending machines which work 
by continuous feeding are already known in the prior art. Bending and 
stirrup machines which bend bars, wire or the like in any shape by bending 
either clockwise or counterclockwise have also been developed. 
It has been particularly noticed that a wellknown type of stirrup machine 
utilizes a bending method based on a bending unit with a fixed fork around 
which a bending pin is made to partially rotate clockwise or 
counterclockwise making it re-enter and pass either above or under the 
bending bar. The expulsion of the finished product is caused by a central 
pin which is coaxial to the rotation axis of said bending pin. 
In other cases, this pin acts not only as an expeller, but also as shearing 
element. These first types of machines are at a very advanced basis, but 
they are very complicated and expensive because they require a large 
number of moveable parts. In other cases, said central pin is eliminated 
and the fork is movable axially effacing in order to allow the expulsion 
of the finished product in connection with a shearing unit (U.S. Pat. Nos. 
3,991,600, issued Nov. 16, 1976, and 4,049,026, issued Sept. 20, 1977. 
SUMMARY OF THE INVENTION 
It is accordingly an object of the present invention to overcome the 
disadvantages of the prior art as mentioned above. 
Furthermore, in order to simplify the stirrup machine and to reduce its 
production costs, the invention incorporates a bending unit with a central 
fork and a bending pin which is non-movable axially. The fork is also 
non-rotatable so as to avoid the dragging of the bar during the bending 
phase. 
A guide unit for said stock material to be bent is placed upstream of said 
bending unit, said guide unit being movable transversally in a forward and 
backward direction for pushing said stock material out of the bending 
plane to disengage said bending unit in order to allow the reversing of 
said bending rotation of said bending pin by positioning it under said 
stock material on the opposite side for the reversed bending, and reversal 
of the feed to recall the bent material before the shearing to reduce 
waste. 
In a preferred embodiment of the invention, the shear guide unit comprises 
a movable shear guide and a fixed interchangeable countershear which 
cooperate to shear the stock material when said shear guide moves in 
completely backward beyond said countershear.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
According to FIGS. 1-2, the stirrup machine consists of a well-known 
feeder-retractor unit 1 for the stock material 2; a shear guide unit 3 for 
the stock material 2; a bending unit 4 for the stock material 2; a 
conventional electronically programmable control means 10 to drive the 
above-mentioned units, not illustrated and well-known in the field. 
The shear guide unit 3 consists of an interchangeable transversally movable 
shear guide 5 and a fixed interchangeable countershear 6, placed adjacent 
to the stock material 2 between said shear guide 5 and said bending unit 
4. The stock material 2 is sheared by moving the shear guide 5, and hence 
the stock material 2 toward the fixed countershear 6. The relative 
movement of the end of the shear guide 5 against the end of the 
countershear 6 shears off the stock material 2 protruding from the end of 
the shear guide 5. 
The shear guide 5 is shaped as a piece of pipe to guide and advance within 
it said stock material 2. 
The bending unit 4 consists of a fixed interchangeable central fork 7 and a 
rotatable bending pin 8, mounted on a rotatable bending disc 9 positioned 
adjacent to said central fork 7. 
Referring to one of the possible methods for preparing stirrups, the 
operating units work as follows: 
1. The feeder-retractor 1 causes the stock material 2 to proceed forward to 
a desired extent in a conventional manner, such as with an electronic 
system of counter-pulses. This allows the stock material 2 to pass through 
the shear guide 5, adjacent the fixed countershear 6 and through the fork 
7 (FIGS. 3-4). 
2. The bending disc 9 with the bending pin 8, which is in position on one 
side of the stock material 2, will initiate a first bending of the stock 
material 2 by rotating, for instance, in a clockwise direction against the 
stock material as shown in FIGS. 5-6. 
3. After this, the disc 9 and the bending pin 8 return to their original 
position (FIGS. 7-8), while a predetermined length of the stock (2) is 
moved through the machine (FIGS. 9-10). 
4. The shearing unit 5 then shifts forward to push the stock material 2 out 
of the bending plane of the bending pin 8 (FIGS. 11, 12, 13). The disc 9, 
and hence the bending pin 8, is then rotated to the opposite side with 
respect to the stock material 2 by means of a clockwise rotation (FIGS. 
14, 15). 
5. The shear guide 5 next pulls the stock material back to the normal 
position in the bending plane of the bending pin 8 (FIGS. 16, 17), and 
another bending is performed by rotating the disc 9, and hence the pin 8, 
counterclockwise (FIGS. 18, 19). 
6. When the stirrup is completed, the shear guide 5 shifts forward pushing 
the stock material 2 out of the bending plane (FIGS. 20, 21, 22). 
7. The bent stock material 2 is then withdrawn by means of the 
feeder-retractor unit 1 (FIGS. 23, 24). 
8. The shear guide 5 is then retracted toward and beyond the edge of the 
fixed countershear 6 and the stirrup is cut-off from the stock material 2 
at the desired point (FIG. 25). 
Obviously, the invention is not limited to the above-described and 
illustrated embodiments; on the contrary, they can be considered as the 
base of other forms and ways of realization whose executing details may 
vary without exceeding the essence of the stated and herein-described 
disclosure. 
It will be obvious to those skilled in the art that various changes may be 
made without departing from the scope of the invention and the invention 
is not to be considered to be limited to what is shown in the drawings and 
described in the specification.