US2974379A

US2974379A - Die casting machines

Info

Publication number: US2974379A
Application number: US674501A
Authority: US
Inventors: Mills Aubrey Robert
Original assignee: Die Casting Machine Tools Ltd
Current assignee: Die Casting Machine Tools Ltd
Priority date: 1956-07-27
Filing date: 1957-07-26
Publication date: 1961-03-14
Anticipated expiration: 1978-03-14

Description

March 14, 1961 A. R. MILLS 2,974,379

DIE CASTING MACHINES Filed July 26, 1957 5 ZA/ Men/7214:

United States Patent 2,974,379- DIE CASTING MACHINES Aubrey Robert Mills, London, England, assignor to Die Casting Machine Tools Limited, London, England, a British company Filed July 26, 1957, Ser. No. 674,501

Claims priority, application Great Britain July 27, 1956 1 Claim. (Cl. 22-67) This invention relates to die casting machines of the kind, hereinafter referred to as the kind described, having two dies which are brought together to form a mould into which the casting material is injected and are then moved apart -for the casting to be ejected.

According to this invention, in a die casting machine of the kind described, means are provided for brushing the dies after they have been moved apart. Most conveniently, said means are actuated automatically by, or in timed relation with, the die moving means. For example, a micro-switch may be arranged tobe operated by the die moving means or by a part connected thereto,

which micro'switch controls an electrical circuit for initiating the operation of means for moving the brush over the die, which means may comprise an air-operated piston and cylinder assembly.

The brushing of the dies serves to keep them clean and preferably is etfected by a wire brush or brushes. Such brush or brushes may be arranged not only to clean the faces of the dies but also, if necessary, to lubricate the dies and/or to put graphite solution on the dies as is sometimes required when new dies are taken into service. It will be appreciated that in die casting machines, it is the common practice to have one stationary die and one moving die and to have one or more ejector pins passing through the moving die plate and extending in the direction of movement thereof, which pins are held stationary when the dies are moved apart so that the pins force the casting from the moving die. Such ejector pins require periodical lubrication and, particularly in die casting machines operating automatically for the repetitive production of castings, regular lubrication is necessary and is conveniently eflected by brushing in the man ner described above.

The aforementioned means for brushing the dies conveniently comprise two brushes arranged back-toback and suitably shaped so as to brush the surface of the two dies respectively. It will be understood that the brushes would have to pass between or around the ejector pins, and/or any cores which may be required in the mould.

vThe brushes themselves will, in general, ensure positive ejection of the casting but a suitable projection or the like may be provided on the brushes or on the brush operating means for this purpose.

In the following description reference will be made to the accompanying drawing in which Figure 1 is a perspective view of part of a die casting machine; and

Figure 2 is a scrap end view of a brush and part of the brush operating mechanism.

Referring to the drawings, there is shown a fixed die plate and a movable die plate 1 2 which can be closed together to form a mould. The fixed die plate 10 is mounted on a platen 12 through which molten metal from a suitably heated bath 13 can be injected into the mould by means of a plunger (not shown) operated by a compressed air piston and cylinder assembly 14. The

"i1 ce movable die plate .=1 1 is slidable on tour guide bars 15 arranged at the :four corners of the die plates and is moved by means of a toggle linkage 16, this toggle linkage conveniently being operated by another compressed air piston and cylinder assembly (not shown).

The apparatus thus far described may be of known construction. The present invention is concerned more particularly with the provision of means for brushing the die plates and -for this purpose there is provided a pair of

brushes

20, 21 mounted back to back on a brush holder 22 which brush holder is mounted on the piston of a further compressed air piston and cylinder assembly 23. The piston and cylinder assembly 23 is carried on a plate 24 supported on the horizontal part of an L-shaped member 25, the upright portion of which is bolted to the aforementioned platen 1'2. The L-shaped member 25 preferably has vertical slots through which pass the bolts for bolting the member to the platen 12 arranged so that the member 25 and hence the brush operating cylinder 23 may be raised or lowered as required to accommodate the provision of different sized die plates in the machine. Furthermore the plate 24, as shown has slots 26 for bolts 27 by which it is bolted to the horizontal part of the member 23 so that the plate 24 may be adjusted in position in the direction of movement of the movable die plate 12 thereby permitting of adjustment of the position of the

brushes

20, 21 for die plates of varying thickness. To prevent any twisting of the piston and brush assembly about the cylinder axis, there is secured to the brush holder 22 a rod 28 (Figure 2) extending parallel to the axis of the cylinder 23 and passing through a bush in the plate 24. To control the op eration of the cylinder 23, there is provided a microswitch 30 operated by the movable die plate .11 or part attached thereto or moving in synchronism therewith and this switch is shown in Figure 1 as being positioned so as to be operated by the movable die plate 11 when the latter reaches the position of maximum opening of the die plates. This switch 30, by means of an electrical connection 31, controls a solenoid-operated changeover valve 32 for reversing the connections of the air supply 33 to the ends of the cylinder 23 and so causes the

brushes

20, 21 to be moved downwardly between the two die plates 10, 12. A further switch 34, operated by a projection 35 on the aforementioned guide rod 28 is provided for returning the reversing valve 32 to its normal position when the

brushes

20, 21 have reached the lower limit of their travel.

Lubricating means indicated diagrammatically by a pipe 36 are provided for spraying a lubricant, such as a graphite solution, onto the brush 21 and a similar lubricating device (not shown) is provided tor lubricating the brush 20. These lubricating means may conveniently be operated by the compressed air from the cylinder 23 but other ways of applying lubricant to the brushes will be obvious to those skilled in the art. The lubricant applied to the brushes is spread by the brushes over the die plates and, in particular, over any ejector pins or cores such as the core 37 and the ejector pins of which the rear ends are shown at 38.

The brush and brush holder serve the further important advantage that they ensure positive ejection of a casting from a mould. This is of particular importance in an automatic machine and, in such a machine, preferably the brush-operating mechanism is interlocked with the die plate operating mechanism to ensure that the die plates cannot be closed together until the brushes have made a full stroke across the dies and back again. In a compressed-air operated machine, the interlocking may be the air valves.

I claim:

A die casting machine comprising in combination, a pair of dies having substantially parallel vertical surfaces and movable horizontally toward each other, to form a mold, and away from each other for removal of a casting; a brush holder supported on said machine above said dies for substantially vertical linear reciprocation between the separated dies; a pair of brushes mounted on said holder in back to back relation and each projecting toward the surface of one of said dies for conjoint cleaning of both die surfaces by reciprocation of said brush holder; at fluid pressure actuator connected to said brush holder for power operation of the latter; control means for said actuator, including a control element in the path of retracting movement of one die operable, when ac- 15 2,054,476

tuated, to condition said control means to energize said actuator to move said brush holder downwardly between said die surfaces; and a second control element operable by said actuator at the limit of such downward movement to condition said control means to energize said actuator to move said brush holder upward-1y; said machine including interlocking means preventing closure of said dies before said brush holder is retracted.

References Cited in the file of this patent UNITED STATES PATENTS Benson Oct. 27, 1868 Korsmo Nov. 23, 1926 Derry et al Sept. 15, 1936