Metal deforming – By use of closed-die and coacting work-forcer – With stripping or ejecting from tool
Patent
1994-10-27
1996-08-06
Larson, Lowell A.
Metal deforming
By use of closed-die and coacting work-forcer
With stripping or ejecting from tool
72427, 470152, B21D 4500, B21D 4502
Patent
active
055422764
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention concerns a method and an apparatus for ejecting an elongate blank from a die in the form of a through-going channel, where one end of the blank has been formed by a tool. Use is made of an ejector rod or pin which is moved into the die against the other end of the blank.
BACKGROUND
In the production of elongate objects, such as e.g. screws, it is a known method to retain a blank in a die, while one end of the blank is formed by one or more tools. The die frequently has the shape of a through-going channel, and during forming the opposite end of the die is frequently closed by a bottom stop or in that the ejector pin forms the bottom of the die. When the blank has been finished, it is to be ejected from the die, and this is done by means of an ejector rod or pin which is moved into the die from the bottom stop end. To ensure that the blank is ejected completely, an ejector pin of substantially the same length as the blank or the die is required. However, a great force is required to release the blank from the die, and this entails the risk that the long pin breaks or bends. This often occurs in existing machines.
So far, it has been attempted to remedy this problem by carrying out some form of lubrication to reduce the force required to eject the blank from the die. Thus, the blank may e.g. be phosphatized. However, this is a both costly and time-consuming solution, which also has environmental drawbacks. Moreover, such lubrication also involves a risk of the blank being unintentionally drawn out of the die when a tool is withdrawn after having formed the head of the blank. Such a blank may get jammed and cause great damage to the vital parts of the machine.
It is also known to prevent deflection or break of the long ejector pin by supporting the pin by a complicated telescopic support; but this is a solution which unduly adds to the manufacturing costs.
SUMMARY OF THE INVENTION
From DE-C-867 944 a device is known in which the blank is first released in that an ejector rod or pin, short with respect to the length of the die, moves the blank a short distance, and the blank is then ejected completely from the die using another ejector rod or pin.
The invention provides a method ensuring that the blank can be ejected from the die without any risk of ejector pin deflection or break. Furthermore, control measurement of the blank ejected from the die can be obtained in a simple manner.
This is obtained according to the invention in that ejection thus takes place in two steps. First, the blank is loosened and pushed slightly out of the die by a short ejector pin. Since this pin is short, there is no risk of pin deflection or break, even though a quite great force is frequently used. Once the blank has been loosened by this pin, it can be pushed out of the die by a relatively small force. This can therefore take place using a long ejector pin without any risk of said pin breaking or bending.
A simple control facility for the ejected blank is obtained when the first ejector rod or pin moves the blank a well-defined distance toward a control unit adapted to produce a signal in response to the geometry of the blank. An apparatus according to the invention comprises a first relatively short eject rod or pin adapted to move the blank a relatively short distance, and a second ejector rod or pin adapted to eject the blank from the die, said second pin having essentially the same length as the die.
The apparatus moreover comprises a control unit so arranged that the first ejector rod or pin moves the blank a well-defined distance toward the control unit, which is adapted to produce a signal in response to the geometry of the blank. The apparatus is hereby capable of performing control measurements of the ejected blank in a simple manner, since the control unit can decide whether a given blank is to be accepted or rejected on the basis of the size of the signal.
In a special embodiment mentioned in claim 3 the control unit is formed by a slot detector adapted to produce a signal i
REFERENCES:
patent: 1856440 (1932-05-01), Spire
patent: 4050283 (1977-09-01), Schober
patent: 4370878 (1983-02-01), Carrieri
Frandsen Jesper
Nielsen Ove
Butler Rodney A.
Enkotec A/S
Larson Lowell A.
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