Plastic article or earthenware shaping or treating: apparatus – With apparatus assembly or dismantling means or with idle part – Pivotally joined housings or housing sections enclosing...
Reexamination Certificate
1999-01-26
2001-08-14
Nguyen, Nam (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
With apparatus assembly or dismantling means or with idle part
Pivotally joined housings or housing sections enclosing...
C425S19200R
Reexamination Certificate
active
06273703
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an extruder head. More particularly this invention concerns such a head having at least two pivoted parts.
BACKGROUND OF THE INVENTION
An extruder head is known which is used to make complex parts of different resins. Such a head is connected to a plurality of extruders and has head parts each forming a passage having an upstream end connected to a respective one of the extruders and a downstream end opening at a die. The various resins are forced at very great pressure, often in excess of 500 bar, along the respective passages to merge at the die and form a workpiece of the desired shape.
It is necessary to be able to open up such a head assembly, for servicing and cleaning and for changing the die. Accordingly German patent 4,234,280 of Kaufmann and US Pat. No. 4,824,353 and 5,851,561 both of Hirschkorn propose systems where the head parts are pivoted on a stationary mold part so that they can be moved between positions where their downstream passage ends merge at the die and positions with their downstream ends separated and the passages exposed.
Such system are all very bulky and difficult to maintain tightly together under the enormous working pressures of the extrusion apparatus. Accordingly hydraulic locks are provided which clamp the head parts to the stationary head part. Such locks normally are constituted as hydraulic cylinders carried on the stationary part and having piston rods that engage formations of the respective head parts to pull same solidly together and against the stationary part.
While these arrangements are relatively effective, they do not completely rule out shifting of the head parts and, therefore, leakage from between the movable parts of the extruder head. The cylinders must exert considerable clamping force in order to hold the interfaces between the head parts together even though they usually are able to effectively prevent leakage between the head parts and the actual mold.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide an improved extruder head with pivotal parts.
Another object is the provision of such an improved extruder head with pivotal parts which overcomes the above-given disadvantages, that is which can be operated at very high pressure without fear of leakage from between the head parts.
SUMMARY OF THE INVENTION
An extruder head has according to the invention a stationary head part and upper and lower head parts pivotal about respective upper and lower axes on the stationary part between inner positions closely juxtaposed with each other and with the stationary part and outer positions separated from each other and from the stationary part. Respective upper and lower latches engageable between the respective movable head parts and the stationary head part retain the movable parts against the stationary part. According to the invention a crosswise latch engageable between the movable head parts retains the movable parts against each other in the inner positions thereof.
This crosswise latch therefore is effective between the movable parts, that is latches one to the other. It normally extends across an interface plane between these parts so it is highly effective in holding them together at this interface plane. In addition the farther this crosswise latch is spaced from the pivot axes of the movable parts, the greater the mechanical advantage and the more strongly it will hold together the two movable parts.
According to the invention the crosswise latch includes an actuator mounted on one of the movable head parts and a retaining member engageable with the other of the movable head parts. The actuator is a hydraulic cylinder having a piston rod forming the retaining member. More particularly the cylinder is mounted on the upper movable head part.
For a very compact construction the lower movable head part has a formation with a face extending crosswise of the piston rod and engageable therewith. The piston rod has a head pivotal between a position engageable with the face and a position movable past the face. The lower movable head part is formed with a passage generally complementary to the head and through which the head is movable. The face is formed at an end of the passage. Thus the piston rod passes through the passage once the movable mold parts are in the inner position, and then the piston rod is advanced, rotated, and retracted to lock the two movable parts together.
Normally in accordance with the invention the crosswise latch includes two such actuators and respective retaining members spaced apart parallel to the axes.
REFERENCES:
patent: 4354814 (1982-10-01), Grimminger et al.
patent: 4372736 (1983-02-01), Gooch et al.
patent: 4824353 (1989-04-01), Hirschkorn
patent: 5472332 (1995-12-01), Gohlisch et al.
patent: 5720986 (1998-02-01), Gohlisch et al.
patent: 5851561 (1998-12-01), Hirschkorn
patent: 42 35 280 (1993-10-01), None
Dubno Herbert
Leyson Joseph
Nguyen Nam
ThyssenKrupp AG
Wilford Andrew
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