GB2265098A

GB2265098A - Centrifugal casting machine; plug handling apparatus therefore incorporating an electromagnet

Info

Publication number: GB2265098A
Application number: GB9206200A
Authority: GB
Inventors: Douglas Samuel Gibson; Martin Douglas Gibson
Original assignee: GIBSON CENTRI TECH Ltd
Current assignee: GIBSON CENTRI TECH Ltd
Priority date: 1992-03-21
Filing date: 1992-03-21
Publication date: 1993-09-22
Anticipated expiration: 2012-03-21
Also published as: GB9206200D0; GB2265098B

Abstract

A centrifugal casting machine 10 having a plug or end-plate 14 to close one end of its rotary mould is associated with a plug handling apparatus comprising a carrier arm (21, Fig 1) on which is mounted a holding device (22, Fig 1) comprising an abutment 30 to engage a face of the plug, and an electromagnet 31 to attract and hold the plug and abutment together. The apparatus may comprise a retaining device 38, concentric with the abutment, carried by the arm to urge the plug into the mould as the abutment is retracted from the face of the plug. The abutment may be water-cooled. The plug is held in place during rotation of the mould by clamp 15 mounted on the end 13 of the mould. Safe removal and accurate replacement of plugs is ensured by the use of this plug handling apparatus. <IMAGE>

Description

CENTRIFUGAL CASTING MACHINES AND APPARATUS FOR USE THEREWITH This invention concerns centrifugal casting machines and apparatus for use therewith.

In centrifugal casting machines one end of a hollow, rotatable mould is blocked by a plug, sometimes called an "end plate", which has to be removed prior to extraction of a casting from the mould Such plugs have to be robust to withstand severe thermal and mechanical loads, and are thus heavy and, at the time of removal, very hot.

To minimise the risks to the machine operators, plug handling apparatus has been developed in which hydraulically actuated mechanical grabs mounted on carrier arms are employed to seize and extract such plugs, move the plugs clear of the moulds, and, subsequently, to replace the plugs.

Such apparatus gives rise to a number of problems, including the potential hazard inherent in using hydraulic fluid in close proximity to the end of the mould, the additional cost, weight and bulk required to provide formations on the plugs suitable for accepting the grabs, and the expense involved in constructing and maintaining the grabs so that they function reliably to ensure safe removal and accurate replacement of the plugs without damaging the mould.

To reduce or avoid such problems the present invention provides a centrifugal casting machine having a plug and plug handling apparatus comprising a carrier arm on which is mounted a holding device comprising an abutment to engage a face of the plug, and an electromagnet to attract and hold the plug and abutment together.

The abutment and said face are preferably inclined to the rotational axis of the mould, so that the abutment and face are mutually self-centering as they are drawn together.

The apparatus preferably comprises a retaining device carried by the arm to urge the plug into the mould as the abutment is retracted from said face.

The retaining device is preferably concentric with the abutment.

The electromagnet is preferably located within the abutment; and preferably has a soft iron core. The core preferably serves as a housing for part of the retaining device.

The machine or the apparatus is preferably provided with a water cooling arrangement, for cooling the abutment.

The abutment is preferably shrouded peripherally by a clamp actuator arranged to engage plug holding clamps on the mould.

The invention further provides and includes the plug handling apparatus for use in conjunction with a centrifugal casting machine; and provides and includes said holding device for attachment to the carrier arm of said apparatus.

The invention will now be described further, by way of example, with reference to the accompanying diagrammatic drawings, wherein: FIGURE 1 shows a simplified plan view of a centrifugal casting machine provided with plug handling apparatus of the invention; FIGURE 2 shows the machine in end elevation; FIGURE 3 is a cross-sectional view of a holding device of said apparatus, and FIGURES 4 and 5 are diagrams showing the holding device in two operational states.

Referring to FIGURES 1 and 2, the casting machine 10 has a rotary mould 11 supported by rollers 12 for driving the mould to rotate about its longitudinal axis. One end 13 of the mould is closed by a plug 14 which is held in place during rotation of the mould by clamp 15 mounted on said end 13. In this embodiment the clamps are of centrifugally operating form, but spring loaded or combined spring and centrifugally based clamps could be employed.

Mounted alongside, e.g. on a common base 16, the machine 10 is plug handling apparatus 20 in which a carrier arm 21 carries, at its free end, a holding device 22. The other end of the arm 21 is mounted on a splined shaft 23 which is carried by bearings 25 so as to be longitudinally slidable in a sleeve 24 by means of a double acting hydraulic ram 26 connected to the other end of the shaft 23.

The sleeve 24 is mounted in bearings 27 for arcuate movement about an axis parallel to the mould axis and is connected by an arm 28 to another double acting hydraulic ram 29.

The holding device 22 comprises an abutment 30 provided on one end of a housing 34 for an electromagnet 31, of cylindrical form, having a core 32. The abutment and core are of a ferromagnetic material such as soft iron, and, together with an annular closure plate 33, enclose the electromagnet. The plate 33 is of nonmagnetic stainless steel. The abutment 30 has a conically chamfered internal face 35.

The core 32 has a stepped bore to accommodate a head 36 and part of a shaft 37 of a retaining device 38 which is movable from the retracted position (FIGURE 3) to an extended position (FIGURE 5) by means of a double acting pneumatic ram 39 mounted on the arm. The head 36 has projecting fingers 40 and is rotatably carried by a bearing 41 on the shaft 37.

The arm 21 also carries a clamp actuator 42 of bowl shape (not shown in FIGURE 3) which peripherally shrouds the abutment 30.

In use, an operator or automatic control system (not shown) can control the apparatus entirely by controlling the three rams 26, 29 and 39.

At the time of completion of a casting operation, when the mould has ceased rotating, the apparatus is brought to the condition shown in FIGURES 1 and if it is not already in this condition, in which the holding device and clamp actuator are co-axial with, and spaced rearwardly from, the mould. Thereafter, to remove the plug, the ram 26 is actuated to move the arm and holding device forwards until the abutment 30 receives an internally chamfered rearwardly projecting male formation 50 on a rear face of the plug. During this forwards movement the clamp actuator 42 strikes the outwardly projecting arms 51 of the clamps 15 to pivot these arms forwards and inwards thereby swinging the plug clamping arms 52 of the clamp clear of the plug.

The electromagnet is then energised to draw or hold together the plug and abutment which have been brought into mutual concentricity by interengagement of the face 35 and the formation 50 (FIGURE 4); the ram 26 is actuated to shift the shaft 23 rearwards to move the holding device, with the plug thereon away from the rear end of the mould; and the ram 29 is actuated to swing the arm 21 upwards through a substantial arc, e.g. of some 4OC, so that the plug is moved clear of the mould to enable a mechanism (not shown) to be brought to the rear end of the mould for removal of the casting.

After removal of the casting, the mould and plug are prepared for the next casting operation, and the plug is then returned to the mould by actuating the ram 29 to swing the arm downward until the mould and holding device are co-axial, and actuating the ram 26 to move the holding device forwards until the plug is thrust home into the mould.

Thereafter, the electromagnet is de-energised and the ram 39 is actuated to thrust the retaining device 38 forwards so that the fingers 40 abut the plug, and the ram 39 is held actuated whilst the ram 26 is actuated to move the arm rearwards until the holding device and clamp actuator 42 are spaced rearwardly a centimetre or more from the mould and the clamps 15 whilst the fingers 40 continue to bear against the plug.

The ram 39 is held actuated as the mould is being driven to accelerate to full rotational speed, so that the plug is held in place until the clamps 15, responding to centrifugal force thereon, become effective to clamp the plug in the mould (FIGURE 5). During this acceleration period, the head rotates on the shaft.

Thereafter, the ram 39 is actuated in the reverse direction to retract the head into the stepped bore.

The invention is not confined to details of the foregoing example and many variations and modifications are possible within the scope of the invention. For example, the holding device is preferably cooled e.g. by a flow of fluid, preferably water, directed onto the holding device, e.g. by a spray jet 53, which may be carried by the arm as indicated in FIGURE 1.

The retaining device may be omitted, especially if spring actuated clamps are used.

The plug handling apparatus may be disposed relative to or mounted on the casing machine in any suitable position, and may comprise any suitable means for manoeuvring the holding device.

The invention further provides a holding device for casting machines having any novel part or feature disclosed herein in the drawings, or any novel combination of parts or features so disclosed.

Claims

1. A centrifugal casting machine having a plug to close one end of a rotary mould, and plug handling apparatus comprising a carrier arm on which is mounted a holding device comprising an abutment to engage a face of the plug, and an electromagnet to attract and hold the plug and abutment together.

2. A machine as claimed in Claim 1 wherein the abutment and said face are inclined to the rotational axis of the mould, so that the abutment and face are mutually selfcentering as they are drawn together.

3. A machine as claimed in Claim 1 or 2 wherein the apparatus comprises a retaining device carried by the arm to urge the plug into the mould as the abutment is retracted from said face.

4. A machine as claimed in Claim 3 wherein the retaining device is concentric with the abutment.

5. A machine as claimed Claim 4 wherein the electromagnet is located within the abutment.

6. A machine as claimed in Claim 5 wherein the electromagnet has a soft iron core.

7. A machine as claimed in Claim 6 wherein the core serves as a housing for part of the retaining device.

8. A machine as claimed in any preceding claim and provided with a water cooling arrangement, for cooling the abutment.

9. A machine as claimed in any preceding claim wherein the abutment is shrouded peripherally by a clamp actuator arranged to engage plug holding clamps on the mould.

10. Plug handling apparatus or a holding device constructed and arranged to constitute the plug handling apparatus or the holding device of the centrifugal casting machine claimed in any preceding claim.

11. Plug handling apparatus, a holding device or a centrifugal casting machine substantially as hereinbefore described with reference to the accompanying drawings