GB1564118A - Formation of holes in workpieces - Google Patents

Description

(54) FORMATION OF HOLES IN WORKPIECES (71) We, HERBERT COTTERILL LI- MITED, a British Company of Kirkby Lane, Pinxton, Nottingham, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: The invention relates to the formation of holes in workpieces, particularly to forming holes with non parallel sides in heavy gauge metal parts.

In fabricating heavy duty structures of metal, usually steel, jointing or mounting holes may be required having sides angled other than normally to an originating surface, particularly non-parallel sides as for conical holes to seat or house leg members relative to heavy frame members, for example of mine-roof supports. Typically, such structures are heavy, and large, and yet may require accurate sizing and location of such mounting or housing holes.

Severe handling and/or working space problems may arise where sub-frames or component parts of such structures as mineroof supports have to be moved and manipulated relative to hole producing equipment, or vice versa, in order to produce two or more accurately formed holes, say for component seatings, at precisely spaced locations.

According to one aspect of the invention there is provided apparatus for forming at least two conical holes simultaneously in a workpiece or workpieces, comprising at least two thermal cutters of which at least their jet nozzles are separately adjustable for angles of cut and radial spacings relative to spaced cutter rotation axes, and drive means for rotating the jet nozzles simultaneously about their respective said spaced cutter rotation axes during cutting. Preferably each jet is adjustable to a desired spacing relative to the workpiece. Close control of this spacing allows high accuracy of size and shape of a conical hole that is normally formed from a preformed cylindrical hole.

Preferably, each cutter is adjustable as a whole by rotation relative to the axis of a shaft to which it is rotatably mounted, and that shaft is, itself, rotatably mounted relative to an axis that intersects that of the shaft and, preferably, also intersects the cutter rotation axis. For each cutter, a second shaft, fixed relative to the cutter rotation axis has the first-mentioned cutter carrying shaft mounted relative thereto to be both rotatable and axially adjustable. Adjustment of the angle and radius of the cutter jet relative to the cutter rotation axis, and the height of the jet above the workpiece, may then be made and can result in the axis of the cutter jet being in the same plane as the cutter rotation axis.

Provision will be made for successive cutting operations, or even parts of cutting operations, to involve reversals of rotation of the cutters to avoid winding-up or swivel mounting of supply tubes or pipes.

According to another aspect of the invention there is provided a method of forming two or more conical holes in a workpiece at the positions of pre-drilled holes having diameters equal to or smaller than the smallest diameters of the coresponding desired conical holes, the method comprising, for each said hole, setting a corresponding thermal cutter jet nozzle to a desired radial spacing from a cutter rotation axis and to a desired angle of cut with a desired spacing from the workpiece and rotating the cutters about their respective spaced said cutter axes.

One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic perspective view of equipment for thermal cutting of two holes simultaneously Figure 2 shows details of adjustment for thermal cutter head; Figure 3 shows details of a suitable simultaneous drive mechanism for the cutter heads; and Figure 4 shows, diagrammatically, a gas feed and control system for the cutters.

In Figure 1, a generally horizontal bed 10 is shown for supporting a workpiece (not shown) to have two holes formed therein. A vertical frame part 12 is fixed relative to the bed frame 10 and has mounted thereto two thermal cutters 14 in either fixed or relatively movable relation.

As shown in Figure 2, each cutter comprises a jet 20 on a gas feed head 21 supplied by flexible tube or pipe lines 22, 23 and 24 for propane, and primary and secondary oxygen feeds respectively. The head 21 is fixed to a carrier 25 that is rotatable on a shaft 26 and can be clamped in any desired relative angular position by means not shown. The shaft 26 is itself carried by, and slidable axially of, a carrier 27 rotatable on a further stubshaft 28 that is fixed relatively to, and extends radially of, a head drive shaft 29 in a housing 30. Suitable clamping means will also be provided to secure the shaft 26 in any desired angular position relative to the axis of the stubshaft 28.

Angular adjustment about the axes of these two shafts 26 and 28, which are substantially at right angles, allows the vertical position of the cutter jet 20 to be adjusted and the axis 31 of the cutter head to be inclined at any desired angle relative to the vertical axis 32 of the head drive shaft and yet lie in the same vertical plane. as also indicated at the lower right of Figure 2, for most efficient formation of a conical hole.

This has particular relevance as the height of the cutter jet above the workpiece determines the depth to which cutting will take place and affects the diameter of the hole, and so, ideally is capable of being closely controlled and should be related to the workpiece thickness.

The cutter drive shaft 29 is rotatably mounted in its housing 30 which is secured to the frame part 12. If desired, this housing 30 could include an adjustable coupling mechanism, e.g. spline and collar, for allowing axially adjustment of the shaft 29 for alternative or additional control of the height of the cutter jet. The shaft 29 is driven by a belt 33 via a drive pulley 34.

The drive pulleys 34 of the two cutter heads 14 are shown as lying substantially in the same horizontal plane as an output pulley of reduction gearing 35 for driving the belt which also passes round a pulley 38 on an eccentric belt tensioner 39 also mounted to the frame part 12.

The reduction gearing may be worm and wheel type and is shown driven by a toothed belt 40 from motor output gearing 41.

Motor speed will normally be varied to suit different radii of cut and/or workpiece materials. If desired, either or both of the sets of gearing, may be variable to allow adjustment of cutter rotation speed ranges to suit particular workpiece alloys, thicknesses or large differences of radius of cut.

As indicated in Figure 4, single oxygen and propane feed pipes 41 and 42 are required for the equipment of Figure 1. The propane pipe 42 is shown with a T-fitting to supply individual cutter pipe lines 22 via wheel valves 43. The oxygen input line 41 is branched and fitted to supply both primary and secondary lines 23 and 24 of each cutter head via wheel valves 44 and 45, respectively, and, for the secondary pipes or lines, via solenoid operated valves 46. Operation of these solenoid valves 46 serves to increase the oxygen supply after a pre-heat phase.

Electrical switches and associated warning lights are indicated for solenoid valve control and motor operation for which a forward/reverse and speed control wheel is also indicated.

For a given conical hole the cutter jet angles will be set to give the desired divergence of the hole sides. Normally, the worpiece will be pre-drilled with a hole equal to or smaller than the smallest aperture of the desired conical hole or seating, so as to reduce the amount of material to be removed, give a more suitable surface to cut from and lead to a more efficient cutting operation, compared, that is, to burning straight through the thickness of the workpiece which would involve the generation of high temperatures and the risk of distortion of the workpiece and/or inaccurate holes.

WHAT WE CLAIM IS: 1. Apparatus for forming at least two conical holes simultaneously in a workpiece or workpieces, comprising at least two thermal cutters of which at least their jet nozzles are separately adjustable for angles of cut and radial spacings relative to spaced cutter rotation axes, and drive means for rotating the jet nozzles simultaneously about their respective said spaced cutter rotation axes during cutting.

2. Apparatus according to claim 1, wherein each jet nozzle is adjustable towards and away from the workpiece to achieve desired spacing relative thereto.

3. Apparatus according to claim 1, or claim 2, wherein, at least during hole forming, each jet nozzle is angled away from said axis.

4. Apparatus according to any preceding claim, wherein each cutter is bodily rotatable on a first shaft that is itself rotatable about a further non-parallel axis.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (16)

**WARNING** start of CLMS field may overlap end of DESC **. view of equipment for thermal cutting of two holes simultaneously Figure 2 shows details of adjustment for thermal cutter head; Figure 3 shows details of a suitable simultaneous drive mechanism for the cutter heads; and Figure 4 shows, diagrammatically, a gas feed and control system for the cutters. In Figure 1, a generally horizontal bed 10 is shown for supporting a workpiece (not shown) to have two holes formed therein. A vertical frame part 12 is fixed relative to the bed frame 10 and has mounted thereto two thermal cutters 14 in either fixed or relatively movable relation. As shown in Figure 2, each cutter comprises a jet 20 on a gas feed head 21 supplied by flexible tube or pipe lines 22, 23 and 24 for propane, and primary and secondary oxygen feeds respectively. The head 21 is fixed to a carrier 25 that is rotatable on a shaft 26 and can be clamped in any desired relative angular position by means not shown. The shaft 26 is itself carried by, and slidable axially of, a carrier 27 rotatable on a further stubshaft 28 that is fixed relatively to, and extends radially of, a head drive shaft 29 in a housing 30. Suitable clamping means will also be provided to secure the shaft 26 in any desired angular position relative to the axis of the stubshaft 28. Angular adjustment about the axes of these two shafts 26 and 28, which are substantially at right angles, allows the vertical position of the cutter jet 20 to be adjusted and the axis 31 of the cutter head to be inclined at any desired angle relative to the vertical axis 32 of the head drive shaft and yet lie in the same vertical plane. as also indicated at the lower right of Figure 2, for most efficient formation of a conical hole. This has particular relevance as the height of the cutter jet above the workpiece determines the depth to which cutting will take place and affects the diameter of the hole, and so, ideally is capable of being closely controlled and should be related to the workpiece thickness. The cutter drive shaft 29 is rotatably mounted in its housing 30 which is secured to the frame part 12. If desired, this housing 30 could include an adjustable coupling mechanism, e.g. spline and collar, for allowing axially adjustment of the shaft 29 for alternative or additional control of the height of the cutter jet. The shaft 29 is driven by a belt 33 via a drive pulley 34. The drive pulleys 34 of the two cutter heads 14 are shown as lying substantially in the same horizontal plane as an output pulley of reduction gearing 35 for driving the belt which also passes round a pulley 38 on an eccentric belt tensioner 39 also mounted to the frame part 12. The reduction gearing may be worm and wheel type and is shown driven by a toothed belt 40 from motor output gearing 41. Motor speed will normally be varied to suit different radii of cut and/or workpiece materials. If desired, either or both of the sets of gearing, may be variable to allow adjustment of cutter rotation speed ranges to suit particular workpiece alloys, thicknesses or large differences of radius of cut. As indicated in Figure 4, single oxygen and propane feed pipes 41 and 42 are required for the equipment of Figure 1. The propane pipe 42 is shown with a T-fitting to supply individual cutter pipe lines 22 via wheel valves 43. The oxygen input line 41 is branched and fitted to supply both primary and secondary lines 23 and 24 of each cutter head via wheel valves 44 and 45, respectively, and, for the secondary pipes or lines, via solenoid operated valves 46. Operation of these solenoid valves 46 serves to increase the oxygen supply after a pre-heat phase. Electrical switches and associated warning lights are indicated for solenoid valve control and motor operation for which a forward/reverse and speed control wheel is also indicated. For a given conical hole the cutter jet angles will be set to give the desired divergence of the hole sides. Normally, the worpiece will be pre-drilled with a hole equal to or smaller than the smallest aperture of the desired conical hole or seating, so as to reduce the amount of material to be removed, give a more suitable surface to cut from and lead to a more efficient cutting operation, compared, that is, to burning straight through the thickness of the workpiece which would involve the generation of high temperatures and the risk of distortion of the workpiece and/or inaccurate holes. WHAT WE CLAIM IS:

1. Apparatus for forming at least two conical holes simultaneously in a workpiece or workpieces, comprising at least two thermal cutters of which at least their jet nozzles are separately adjustable for angles of cut and radial spacings relative to spaced cutter rotation axes, and drive means for rotating the jet nozzles simultaneously about their respective said spaced cutter rotation axes during cutting.

2. Apparatus according to claim 1, wherein each jet nozzle is adjustable towards and away from the workpiece to achieve desired spacing relative thereto.

3. Apparatus according to claim 1, or claim 2, wherein, at least during hole forming, each jet nozzle is angled away from said axis.

4. Apparatus according to any preceding claim, wherein each cutter is bodily rotatable on a first shaft that is itself rotatable about a further non-parallel axis.

5. Apparatus according to claim 4,

wherein that further axis for each cutter appertains to a second shaft that is fixed relative to the rotation axis of that cutter.

6. Apparatus according to claim 5, wherein the axis of the second shaft intersects the corresponding cutter rotation axis.

7. Apparatus according to claim 4, 5 or 6 wherein the axis of the first shaft of each cutter intersects the corresponding further axis.

8. Apparatus according to any one of claims 4 to 7, in which each intersection is orthogonal.

9. Apparatus according to any preceding claim, wherein each cutter rotation axis appetains to a cutter drive shaft having a rotational drive coupling.

10. Apparatus according to claim 9, wherein each cutter drive shaft is disposed at right angles to a drive belt plane through a pulley or pulleys constituting its said drive coupling, a belt tensioner, and a belt drive pulley.

11. Apparatus according to claim 10, in which each cutter drive shaft is vertical.

12. Apparatus according to any preceding claim, further comprising, for cutters, a fuel gas supply line and primary and secondary oxygen supply lines with valve gear whereby the secondary oxygen line is opened after a pre-heat phase utilising the primary oxygen line and the gas supply line.

13. Apparatus for forming holes in workpieces arranged and adapted to operate substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

14. A method of forming two or more conical holes in a workpiece at the positions of pre-drilled holes having diameters equal to or smaller than the smallest diameter of the corresponding desired conical holes, the method comprising, for each said hole, setting a corresponding thermal cutter jet nozzle to a desired radial spacing from a cutter rotation axis and to a desired angle of cut with a desired spacing from the workpiece, and rotating the cutters about their respective spaced said cutter axes.

15. A method according to claim 14, wherein, after said setting, the cutter jet nozzles are each directed to produce a cutting jet with an axis sharing a vertical plane with the corresponding cutter rotation axis.

16. A method forming holes in a workpiece substantially as herein described with reference to the accompanying drawings.