GB2076325A - Shakeout device for moulding equipment - Google Patents

Abstract

A shakeout device for a moulding equipment for use in a foundry comprises a roller transport system (16) for mould boxes (10) and a raisable and lowerable moulded article holding table (18) in a moulding and shake out station to engage under each mould box, the table being connectible to each box to enable vertical displacement thereof with the table. The table is associated with a mould box support surface formed by self-aligning elements (32, 34) which, during a shakeout operation of the table, take over support of the box from conveying rollers. <IMAGE>

Description

SPECIFICATION Shakeout device for moulding equipment The present invention relates to a shakeout device for plant and moulding machines for use in foundries, and has particular reference to those types of plants in which mould boxes are automatically conveyed to a moulding station and thence to downstream work stations. At the moulding station, a moulded article support plate pushes, from beneath, the box upwards, and when the box reaches a certain height it is locked in place and filled with sand, which is then tamped by the usual means.

The moulding being thus carried out, the plate descends s together with the mould box, stopping when reaching the height of the transport plane. The plate continues on down, thus starting the shakeout operation proper, at the end of which the box is conveyed away from the moulding station and is replaced by a further mould box.

The operations described so far are characteristic of equipment known in the art. However, the continuous use of the mould boxes results in their deformation, due in particular to the high temperatures to which they are submitted during casting operations.

Thus it often happens that after a period of use, due to the aforementioned deformation the lower surface of the mould box no longer perfectly conforms to the support plane provided by the shakeout rollers or push rods of the transport and support system at the moulding station.

Due to this inexact support state, when the shakeout operation starts, the mould box is constrained to adopt a different support position on the rollers. This relative displacement between the mould box and table induces stress on the tamped sand, which in some cases may lead to breakage of less resistant parts and of parts which give rise to difficulties in the shaking out.

To avoid this inconvenience, the bearing surfaces of the mould box were periodically submitted to grinding operations aiming at restoring their planarity. These operations, apart from the cost involved, over a period of time result in an unacceptable reduction in the depth of the mould boxes, which accordingly had to be scrapped and replaced.

In view of the high unit cost of the mould boxes and of consequent production losses, it has become necessary to find a solution to the problem, in particular by creation of a uniform support plane for strained mould boxes, i.e. a plane capable of adapting itseif, whenever necessary, to any possible deformation suffered by the plane of the support surface of the mould boxes.

According to the present invention there is provided a shakeout device for moulding equipment, comprising roller conveying means for conveying mould boxes to and from an article moulding and shakeout station, a raisable and lowerable model support table arranged at the station to be engageable under each box when at the station and connectible to the box to enable upward and downward movement thereof with the table, and mould box support means arranged at the station and comprising a plurality of conveying rollers for receiving each box from and returning the box to the roller conveying means, and a plurality of self-aligning support elements for supporting each box in place of the conveying rollers during a shakeout operating phase of the table.

Expediently, the support elements comprise four hydraulic cylinders with pistons so operated as to constitute self-aligning bearing elements adaptible to the support plane of a mould box during the shakeout operation.

Associated with the cylinders may be a locking system for the pistons, whereby the movement of the mould box relative to the table can be stopped while the table, which continues to travel downwards, can carry out the shakeout operation correctly.

An embodiment of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings in which: Figure 1 is a schematic perspective view of moulding equipment including a shakeout device according to the said embodiment of the present invention, Figure 2 is a schematic elevation of the equipment of Fig. 1, Figure 3 is a schematic elevation of a seif- aligning support element of the shakeout device, Figure 4 is a cross-section on the line 4-4 of Fig. 3, and Figure 5 is a schematic cross-section of a support table of the shakeout device and diagram of associated control means.

Referring now to the drawings, in Fig. 1 there is shown a moulding box 10 consisting of four vertical side walls 12, and of an upper frame 1 4 and a lower frame 1 5 bordering the side walls. By sectioning the box 10 in vertical planes parallel with its transverse and longitudinal axes, the wall configuration would have the shape of a "C".

This configuration depends on the transfer system for the moulding boxes to and from a moulding and shakeout station, this transfer system comprising roller guides 16.

During travel towards the station, the box rests on the rollers by way of the lower surface of its upper frame 1 4 and it is pushed onto the conveying rollers by pneumatically operated arms. In the region of the station, the roller walls are positioned with the rollers arranged according to a lower line in such a manner as to cause the moulding box to rest thereon by way of the lower surface of the lower frame 1 5 (Fig. 2) and to be able to make the vertical translations required by the moulding and shakeout operations, as described in the following.

Arranged in the moulding station is a moulded article support table 18, which is provided with two vertical pins 20 to fit into the corresonding holes provided on the frames 14 and 1 5 of the box 10. The part bearing table 1 8 is rigidly connected with the rod 24 of a piston 26 sliding in a single acting pneumatic cylinder 25 (Fig. 5) and it follows the movement of the rod, being guided in and supported by a body 29.

Connected with the internal wall surfaces of plates 30 (Fig. 2) are four small cylinders 32 provided with pistons 34, the function of which will be described in detail in the following.

A cam 38 is connected by means of rod 36 with the table 1 8 and, by means of its movement with the table, operates a number of valves controlling the phases of the moulding and shakeout cycles, as will be described in more detail in connection with Fig. 5.

Figs. 3 and 4 show one of the four cylinders 32, in the upper part of which is engaged the piston 34, which is hydraulically operated. The operating oil, stored in tanks 102 and 108 (Fig. 5), is fed to the cylinder from below through a bore 42 (Fig. 3), a circular chamber 44, ducts 46, a bore 48, and a bore 50 (Fig. 4). In the lower part, the cylinder is provided with a valve to prevent the flow of the oil and thus to cause the piston 34 to be held in a given position. This value consists of a small piston 52 sliding inside a bushing 54 and having a frustoconical end portion engaging in a valve seat 56, which connects the ducts 46 with the bore 48. The opposite side of the piston 52 is connected with air intake 60, which is connected in its turn with pneumatic equipment operating the whole shakeout device.

Also present in each cylinder 32 is a duct 62 (Fig. 3) to convey oil to the upper part of the cylinder via a bore 64 to move the piston downwards.

The operation of the device will now be described with reference to Fig. 5, in which, for the sake of simplicity, only the elements directly involved in the working of the device are shown.

The lines 1 53 and 153' represent a general air supply, and the lines 149 and 1 51 are connected with the rest of the pneumatic circuit. The line 151 is under pressure in the lifting phase of the table 1 8 and in relief in the lowering phase thereof, whereas the line 149 is in relief in the lifting phase and under pressure in the lowering phase. When a moulding box 10 reaches the moulding station, it causes a pneumatic signal to be sent to a pre-working valve 1 50 through the line 151. This valve 150 opens to link the general air supply line 1 53 with the pilot of a valve 154, which opens and feeds to the cylinder 25 air to push the piston 26, table 1 8 and box 10 upwards.When the table 18, in its travel upwards, reaches a height at which its cam causes a valve 1 66 to open, a pneumatic "opening" signal is sent to a valve 100, which is connected with the main supply line 153'. Consequently, compressed air is fed to the tank 102 to force oil from the tank through a duct 104 and into the cylinders 32 to push the shakeout pistons 34 upwards.

On reaching the upper end of its travel, the table 18 operates, by means of the cam 38, a valve 1 68. This is opened and sends air from the line 151 to the pilot valve 170, causing this to open. The air is then fed to a doubleacting cylinder 173, pushing its piston 1 75 to the left and operating a mechanical block 1 77 for the rod 24 of the piston 26. The box 10 is thus secured in its sand loading and tamping position for the moulding operation. At the end of this operation, the descent phase begins.The valve 1 68 is discharged via the line 151, which enters into its discharging phase, and the valve 1 70 is operated through the line 149, which is activated to send the air to the cylinder 1 73 in order to urge the piston 1 75 to the right and release the piston 26. At the end of its travel, the piston 1 75 opens a valve 1 44 and consequently air is fed from the line 149 to the pilot valve 1 50 which is operated to place the valve 1 54 in a discharge condition.

On relief of the feed to the pistons 26, these together with the box 10 and table 1 8 start to descend under the force of gravity. At the beginning of its descent travel, the table 18, through the cam 38, operates the valve 1 66 so as to allow the air discharged from the tank 102. The box 10 rests, in its descent, on the pistons 34, which self-align and form a safe support for the box. At the end of a travel of about 100 mm, the cam 38 operates a valve 180, which sends a pneumatic signal to operate a valve 1 82. The air reaches the intakes 60 (Fig. 4) through a feed line 106, thus operating the valves 51. The pistons 52 (Fig. 4) are pushed against their seats 56 and close the oil ducts 48. The box 10 is thus locked in place and is supported by four pads of oil between the pistons 52 and pistons 34 (Fig. 4).

The table 1 8 continues to descend, thus carrying out the shakeout operation in favourable conditions without any danger of provoking fractures in weaker parts of the moulded article. When reaching its lowest position, the cam 38 leaves the pilot lever of the valve 180, so that the valve 1 82 is operated again on the discharge phase, thus bringing again the valves 51 into inoperative states. In this position, the valve 1 64 is operated, which in turn operates the valve 110 to feed air from the line 1 53 to the tank 108. Thus the oil operates the pistons 34 in the cylinders 32 urging them downwards so that the box 10 at the end of its downward travel can rest on the conveying rollers and leave the moulding station.

Claims (5)

1. A shakeout device for moulding equipment, comprising roller conveying means for conveying mould boxes to and from an article moulding and shakeout station, a raisable and lowerable model support table arranged at the station to be engageable under each box when at the station and connectible to the box to enable upward and downward movement thereof with the table, and mould box support means arranged at the station and comprising a plurality of conveying rollers for receiving each box from and returning the box to the roller conveying means, and a plurality of selfaligning support elements for supporting each box in place of the conveying rollers during a shakeout operating phase of the table.

2. A device as claimed in claim 1, wherein each of the support elements comprises a respective piston-cylinder unit, control means for causing the pistons of the units to engage surface portions of a box at the station and for permitting the pistons to be displaced by the box relative to the table during descent of the table thereby to cause the pistons to be aligned in the plane of said surface portions, and stop means for arresting such displacement of the pistons while the table is still descending.

3. A device as claimed in claim 2, the stop means comprising a respective flow control valve associated with each piston-cylinder unit and operable to prevent a flow of fluid permitting displacement of the piston of that unit relative to the table.

4. A device as claimed in claim 3, wherein each flow control valve comprises a valve housing attached to the cylinder of the associated piston-cylinder unit and a valve piston slidably engaged in the housing, the valve piston being co-operable at one end thereof with a valve seat of the housing.

5. A shakeout device for moulding equipment, the device being substantially as hereinbefore described with reference to the accompanying drawings.