GB2072076A - Improvements in water tables for use with burning machines - Google Patents

Abstract

A water table for use with a burning machine comprises an open-topped water tank 1, a burning platform 4 extending across at least part of the tank, and support means for the burning platform 4, which support means are adjustable vertically, for example hydraulically, in a manner to vary the level of the burning platform with respect to the surface of water in the tank. Thus by vertically adjusting the position of the burning platform the workpiece carried by the platform may be positioned below, at or above the surface of the water, and the burning platform may also be raised to a convenient height for positioning or removal of the workpiece. A sloping floor 6 is provided beneath the burning platform so that, as the platform is raised, the downward flow of water over the floor cleans it of slag which has fallen through the burning platform. <IMAGE>

Description

SPECIFICATION Improvements in water tables for use with burning machines The invention relates to water tables for use with burning machines such as oxy-fuel, gas and plasma cutting machines.

The object of using a water table in conjunction with such burning machines is to provide beneath the burning platform a water tank into which falls the slag and swarf produced during the burning operation. The arrangement may be such that the work being cut is supported at the surface of the water in the tank, or just above or below the water surface.

Besides collecting the slag and swarf produced in the burning operation, the use of the water table also reduces the incidence of fumes, dust and workpiece distortion. The water table may also protect the support bars of the burning platform to reduce distortion, and the water may contain a rust inhibitor and possibly chemicals to assist in the cutting operation or to reduce the hardening effect of cold water coming into contact with the hot workpiece immediately after cutting.

The position of the workpiece in relation to the water surface, i.e. above, at or below the surface, depends on the nature of the burning operation being performed and it is therefore necessary to be able to adjust the relative positions of the workpiece and the water surface. Hitherto this has been achieved by raising and lowering the water level in the tank with respect to a fixed burning platform.

Since such tanks are normally of considerable area the accurate adjustment of the water level with respect to the burning platform may be time consuming. In order to give more rapid control of the water level it has been proposed to provide a waterfilled chamber in communication with the tank, together with means for introducing gas into and exhasting gas from the chamber above the water therein so as to control the water level in the tank.

This is, however, a complex arrangement and the adjustment of the water level in the tank is still not a particularly rapid process.

The present invention sets out to provide an improved form of water table wherein the relative positions of the workpiece and water surface may be rapidly and easily adjusted.

According to the invention there is provided a water table for use with a burning machine, comprising an open-topped container for water, a burning platform extending across at least part of the container, and support means for the burning platform, which support means are adjustable vertically in a manner to vary the level of the burning platform with respect to the surface of water in the container.

Thus by vertically adjusting the position of the burning platform the workpiece carried by the platform may be positioned below, at or above the surface of the water, and the burning platform may also be raised to a convenient height for positioning or removal of the workpiece.

As previously mentioned, the slag and swarf produced by the burning operation are deposited in the water table and it is therefore necessary periodically to clear this material from the water table. Hitherto this has been effected by providing a floor beneath the burning platform onto which the slag and swarf falls, a collection channel being provided to one side of the floor. To deliver the slag and swarf from the floor into the collection channel it has been proposed to have the floor sloping downwardly to the collection channel, but this in itself may be insufficient to ensure that all the slag and swarf passes into the collection channel, and it may therefore be necessary to provide means for mechanically scraping or cleaning the slag and swarf from the floor.In an alternative previously employed arrangement the floor has been so mounted that it may periodically be pivoted upwardly with respect to the water table so that slag and swarf slide under gravity into the collection channel. Both such arrangements are expensive to construct in view of the necessity of providing either cleaning means for the sloping floor or providing for tilting of the floor.

If, in a water table according to the present invention, on the other hand, there is provided beneath the burning platform a sloping floor which is movable with the burning platform, then raising of the burning platform from below the surface of the water to above the surface of the water will result in a flow of water downwardly over the sloping floor, this downward flow of water tending to clean slag and swarf from the sloping floor and deliver it into a collection channel extending along the lower edge of the sloping floor. Thus, in a water table according to the invention, the slag and swarf may be removed automatically by operation of the means forverti- cally adjusting the burning table, and no further slag clearing means needs to be provided.

Where a collecting channel is provided along the lower edge of the sloping floor, means, such as a screw device, may be provided for mechanically displacing material along the channel to a collection point.

In some circumstances it may be advantageous, in a water table according to the invention, also to be able to adjust the relative position of the water surface and workpiece by adjusting the water level. For this purpose there may be disposed beneath the burning platform, and beneath the sloping floor where such is provided, a chamber of variable volume whereby the water level in the container may be varied according to the water displacement effected by said chamber.

The chamber may be such that its effective volume may be varied by introducing gas into or removing gas from the chamber. For example, the chamber may be defined by a downwardly extending, opened-bottomed skirt, the level to which the water rises within the skirt being controlled by the introduction of gas into, or removal of gas from the interior of the skirt.

The drawing(s) originally filed were informal and the print here reproduced is taken from a later filed formal copy.

In any of the above arrangements the vertical adjustable support means for the burning platform may comprise a mechanical linkage operated by hydraulic, electrical or mechanical power means.

The burning platform is preferably removable from the support means.

The following is a more detailed description of various embodiments of the invention reference being made to the accompanying drawings in which: Figure 1 is a diagrammatic perspective view of a water table in accordance with the invention, Figure 2 is a plan view of the water table shown in Figure 1, Figure 3 is a vertical cross-section through the water table showing the burning platform in an elevated position, Figure 4 is a similar view to Figure 3 showing the burning platform in a lowered position, and Figure 5 is a section along the line V-V of Figure 4 showing the sloping floor beneath the burning platform.

Referring to the drawings, the water table comprises a tank 1 containing a liquid, usually water, perhaps with additives, at a fixed level 3. Extending across substantially the whole of the upper part of the tank 1 is a burning platform 4 consisting of equally spaced bars 5. The bars 5 may be permanently fixed on the burning platform or may be replaceable and may be clad, for example by copper, to prevent them being damaged by the cutting action.

As shown in Figure 5, there is fixed beneath the burning platform 4 a solid sloping floor 6 onto which falls slag and swarf produced by the burning operation, this slag and swarf falling between the spaced bars 5 of the burning platform.

The floor 6 comprises two inclined portions 6a which slope downwardly towards one another to meet along the centre line of the tank 1, as shown in Figure 5, the junction between the two parts also sloping downwardly from one end of the tank to the other, As shown in Figure 4. A removable collection basket 9 is disposed within the tank 1 and the open top of the basket 9 is disposed below the lower end of the sloping floor 6 so that slag passing downwardly along the floor 6 falls into the basket.

The burning platform 4 may be raised and lowered to a required height with respect to the water level in the tank 1 by hydraulic, mechanical or similar arrangements. In the arrangement shown the support means for the burning platform is in the form of scissor legs 19 arranged centrally beneath the platform, the opening and closing of the scissor legs being effected by an hydraulic ram 15. This arrangement is shown by way of example only and any other convenient linkage or power means may be provided for raising and lowering the burning platform.

The burning platform may thus be raised and lowered to position the workpiece appropriately with respect to the water surface, as previously described, and may also be raised to the position shown in Figure 3 for positioning or removal of the workpiece.

With the sloping floor 6 arrangement shown, cleaning of slag from the burning table assembly occurs automatically each time the sloping floor is raised above water level. During this operation water flows downwardly over the sloping floor 6 and carries the slag into the basket 9. Thus the slag is cleared every time the burning platform is raised to change or reposition the workpiece.

In order to reduce the total amount of water necessary in the tank, and also to allow the burning platform assembly to come to a stop on the floor of the tank for levelling purposes, a downwardly extending skirt 13 is mounted on the underside of the burning platform. On lowering the burning platform from the position shown in Figure 3, where the whole assembly is above the water surface, air is trapped within the open-bottomed skirt. Consequently lowering of the burning platform assembly raises the water level. A flexible pipe 17 extends from the top of the chamber defined by the skirt to a tap, solenoid valve, or automatic pressure detector valve 18 which opens and allows air to escape from within the skirt so permitting the water level to rise within the skirt and hence to fall to the required height in the tank 1, while the burning platform remains stationary.

A drain tap 14 is fitted to the bottom of the tank 1 for water change if necessary.

The skirt 13 and the means for adjusting the volume of air trapped by the skirt are not essential features of the water table according to the invention and may be omitted if required.

Means may be provided for automatically controlling the water level in the tank. This automatic water level control may be provided by a sealed container 11 (Figure 1) and feed pipe 12 leading from the sea- led container 11 and having the end thereof just above the water surface. Water will only flow into the tank 1 from the sealed container 11 when the water level in the tank 1 drops below the level of the end of the pipe 12 and allows air to run back up the pipe 12 into the sealed container 11. If the skirt arrangement 13 is provided, there will require to be a tap in the pipe 12 to shut the automatic control unit off since the water level will drop significantly whenever the burning platform assembly is raised to the position shown in Figure 3, for example for removal of the workpiece.The operation of the tap in the pipe 12 may be effected manually or automatically.

In an alternative arrangement (not shown) for effecting automatic control of the water level in the tank 1, a scale is fitted to the interior of the tank, the scale having a zero mark level with the top of the burning bars 5. The actual level of the water surface with respect to this datum position can then be read from the scale. A light source above the zero mark is arranged to shine a beam of light downwardly onto a photo-electric cell below the zero mark. Should there be water between the light source and photo-cell the water will refract and diffuse the light so that no signal is received by the photo-cell. The path of the beam of light from the source to the photo-cell may be inclined slightly with respect to the vertical to enhance the refraction effect when water is present.

If no water is present the light beam will be received by the photo-cell and through suitable cir cuitrythe aforementioned solenoid valve 18 will be closed, preventing the water level dropping further.

To obtain the required water level according to the type of work and thickness of the workpiece being cut, the photo-cell may be adjusted vertically with respect to the scale. This can either be effected man ually or the movement may be motorised, a slave scale being provided remote from the water table and near the operator. To prevent the photo-cell being covered with a globule of water even after the water level has dropped below the photo-cell, a domed lens is fitted to it. A hinged cover may be swung around the scale to prevent ripples and water disturbance switching over the lens during opera tion, the cover being open at the top and bottom to allow the water to rise and fall.

The burning platform 4 may be removable from its vertically adjustable support, for example by a crane, to permit rapid change-over of workpieces. Lifting lugs 20 are provided on the platform for this pur pose. Alternatively, the tank 1 could be of three times the length of the burning platform so that two burn ing table assemblies on wheels may be provided within the tank and may be pushed or driven alter nately under the cutting area so that one burning table assembly may be being cleared and reloaded while the other assembly is in use.

Instead of relying solely on gravity and the flow of water to deliver slag from the floor 6 into the basket 9, a channel may be provided along the centre line of the floor 6, a spiral feed, vibrator or endless belt con veyor being provided in the channel to move the slag longitudinally of the channel and into the basket 9. Alternatively, the sloping floor 6 may comprise a single inclined plane, a channel and conveyor being provided across the lower edge of the floor to deliver the slag into a suitable positioned basket.

If required, the basket 9 may be located outside the tank 1, a removable extension being provided for the aforementioned channel so that slag may be deli vered into the basket when the burning platform has been elevated to a raised position above the level of the tank.

Claims (14)

1. A water table for use with a burning machine, comprising an open-topped container for water, a burning platform extending across at least part of the container, and support means for the burning platform, which support means are adjustable verti cally in a manner to vary the level of the burning platform with respect to the surface of water in the container.

2. A water table according to claim 1, wherein there is provided beneath the burning platform, and movable therewith, a sloping floor having at the lower edge thereof means for collecting material passing downwardly along the sloping floor.

3. A water table according to claim 2, wherein said collecting means comprise a fixed open-topped receptacle into which the material falls as it leaves the sloping floor.

4. A water table according to claim 3, wherein the receptacle is disposed within the aforesaid con tainer.

5. Awatertable according to claim 2, wherein said collecting means comprise a channel having means for mechanically displacing material along the channel to a collection point.

6. A water table according to any of the preceding claims, wherein the sloping floor comprises two lateral portions each sloping downwardly to the junction between them, said junction also sloping downwardly to the lower edge of the floor.

7. A water table according to any of the preceding claims, wherein there is disposed beneath said burning platform, and beneath the sloping floor where such is provided, a chamber whereby the water level in the container may be varied according to the water displacement effected by said chamber.

8. A water table according to claim 7, wherein means are provided for varying the effective displacement volume of said chamber.

9. A water table according to claim 8, wherein means are provided for introducing gas into and removing gas from the chamber whereby its effective volume may be varied.

10. A water table according to claim 9, wherein the chamber is defined by a downwardly extending, open-bottomed skirt, the level to which the water rises within the skirt being controlled by the introduction of gas into, or removal of gas from, the interior of the skirt.

11. A water table according to any of the preceding claims, wherein the vertically adjustable support means for the burning platform comprise a mechanical linkage operated by hydraulic, electrical or mechanical power means.

12. A water table according to claim 11, wherein the mechanical linkage comprises one or more scissor-arm assemblies.

13. A water table according to any of the preceding claims, wherein the burning platform is removable from the support means.

14. A water table substantially as hereinbefore described with reference to the accompanying drawings.