GB2221175A - Cutting tool jig - Google Patents

Abstract

The jig (10) for supporting a cutting tool relative to a workpiece e.g. a rail of 'I' shape transverse cross section while the tool cuts an aperture in a vertical portion of the rail, comprises an elongate support member (27) having a profile corresponding with a side of the workpiece, securing means (38) e.g. clamps for securing the support member (27) to the workpiece and locating means (18, 19, 20 and 21) for removably e.g. notches on a support plate (12) locating a component (52 to 57) of the tool so that when a cutting member of the tool is advanced towards the workpiece, the cutting member engages the vertical portion at a predetermined location, through one of apertures (23 to 26). <IMAGE>

Description

Cutting Tool Jig This invention relates to a jig for supporting a cutting tool relative to a workpiece, for example a rail of a railway transport system.

Maintenance of a permanent way of a railway transport system entails providing apertures in vertical webs of rails so that fishplates may be attached to the rails.

The fishplates are secured to sleepers located on ground which supports the permanent way.

Generally, the apertures are arranged in groups of four each spaced the same distance from an adjacentaperture in a longitudinal direction of a rail. The apertures are drilled by means of a drill bit mounted in tool which is located on apparatus for posi#tioning the tool so that the drill bit advances towards a vertical web of a rail in a direction normal to a vertical plane of the web. The apparatus is adapted to support the tool so that - the tool is movable relative to the rail in- a direction longitudinally of the rail. In this manner, the rail may be drilled successively to provide each group of four apertures.

A disadvantage of such apparatus is that it does not provide means for aligning the drill bit accurately at spaced locations corresponding to central axes of the intended apertures. In consequence, it is difficult to position the drill bit with the necessary precision required to ensure that a rail is provided with apertures such that the pitch, or distance between a central axis of one aperture and a central axis of an adjacent aperture, corresponds with the pitch of apertures provided in a fishplate. Since accuracy is a prerequisite to ensure that apertures drilled in a rail have the same pitch as apertures in a fishplate intended to be secured thereto, use of such known apparatus is time consuming, especially if it is being used to lay a permanent way in a darkened environment such as a tunnel.

It is desirable, therefore, to provide a jig for supporting a cutting tool so that the tool may easily be removably located relative to a rail for cutting apertures in the rail at a predetermined pitch without the necessity of having to carry out measurement to determine correct positioning of the tool to effect cutting of successive apertures.

According to the present invention, there is provided a jig for supporting a cutting tool relative to a workpiece comprising a support member for mounting on the workpiece, securing means for securing the support member to the workpiece and locating means for removably locating the tool relative to the support member so that, when a cutting member of the tool is advanced towards the workpiece, the cutting member engages the workpiece at a predetermined location.

A plurality of locating means may be provided being spaced at predetermined distances one from another each for removably locating the tool relative to the support member whereby the cutting member is engageable with the workpiece at a corresponding one of a plurality of locations spaced at predetermined distances one from another.

In this manner, a cutting tool may be sequentially located at each of the locating means whereby the cutting member is sequentially located at predetermined positions for cutting the workpiece, thereby providing apertures at predetermined pitch, without the necessity of carrying out measurement to ensure accuracy of the sequential cutting operation.

Following is a description, by way of example only and with reference to the accompanying drawings, of one method of carrying the invention into effect.

In the drawings: Figure 1 is a front elevation of one embodiment of a jig in accordance with the present invention, Figure 2 is an end elevation of the jig shown in Figure 1.

Figure 3 is a view, corresponding with a lower portion of Figure 2, of another embodiment of a jig in accordance with the present invention in which a location pad has been modified compared with the location pad of the embodiment shown in Figures 1 and 2, Figure 4 is an elevation of the modified location pad shown in Figure 3, and Figure 5 is a cross section on the line V-V of Figure 4. Referring now to Figures 1 and 2 of the drawings, there is shown a jig 10 comprising an elongate rectangular metal plate 11 having a front surface 12, a rear surface 13, an upper surface 14, a lower surface 15 and end surfaces 16,17.

The upper surface 14 is provided with four notches 18, 19,20 and 21 each of which is U-shaped in the plane of the plate 11. Each notch 18 to 21 is equidistant from an adjacent notch 18 to 21. The lower surface 15 of the plate 11 is formed as a series of projections 22 each being contained between axes extending parallel to the end surfaces 16,17 and passing between adjacent notches 18 to 21 or one of the notches 18 and 21 and an adjacent end surface 16,17.

The plate 11 is provided with four apertures 23,24,25,and 26 adjacent the lower surface 15 of the plate 11, the apertures 23,24,25 and 26 being located below the notches 18,19,20 and 21 respectively.

The plate 11 has secured thereto an elongate location pad 27 of substantially U-shape transverse cross section having an inner surface 28, an outer surface 29, an upper longitudinal surface 30 and a lower longitudinal surface 31, the longitudinal dimension of the pad 27 being greater than the longitudinal dimension of the plate 11. The upper longitudinal surface 30 of the pad 27 is welded to the rear surface 13 of the plate 11 and the lower longitudinal surface 31 of the pad 27 is welded to the projections 22 of the plate 11.

The front surface 12 of the plate 11 has welded thereto a hollow elongate box component 32 adjacent the projections 22, the box component 32 being provided with a front plate 32A and four cut-out portions 33,34,35 and 36 corresponding to the apertures 23,24,25 and 26 respectively. The box component 32 is secured to the plate 11 by means of bolts 37 the shanks of which are screwed into nuts (not shown) welded to the front surface 12 of the plate 11.

Portions of the location pad 27 extending beyond the end surfaces 16,17 of the plate 11 each have mounted thereon one of a pair of clamps 38. Each clamp comprises a mounting 39 welded to a base portion of the inner surface 28 of the location pad 27, the mounting having a pair of spaced parallel legs 40,41 extending therefrom and each having an aperture 42 therein. The apertures 42 of the legs 40,41 receive the shank-of a bolt 43 on which is pivotally mounted an end portion of a C-shaped arm 44. The bolt 43 is secured relative to the lugs 40,42 by means of a nut 45.An end portion of the arm 44 remote from the mounting 39 is provided with a threaded bore (not shown) a central longitudinal axis of which is transverse to a central longitudinal axis of the bolt 43 and in which bore there is received an externally threaded rod 46 an outer end portion of which carries an operating handle 47 and an opposite end portion 48 of which comprises a flat surface extending parallel to a base portion of the outer surface 29 of the location pad 27.

The rear surface 13 of the plate 11 may. be provided with a carrying handle 49 and a latch member 50.

The configuration of the jig 10 is such that the jig may be used in co-operation with a cutting tool having an electromagnet for supporting the tool while a cutting member the tool is in operation. An example of such a tool is an ATRA ACE Jetbroach supplied by Nitro Kohki Co.Ltd. The tool will be provided with a locating device 51 according to the present invention comprising--a -cowl 52 having spaced parallel side webs 53,54 and a panel 55 extending at right angles to and between the side webs 53,54, a portion of the panel 55 extending below the side webs 53,54.. The panel 55 is provided with å central aperture 56 in which is received a tubular locating pin 57, the pin 57 being welded to the panel 55. Each of the webs 53,54 is provided with a notch 58 adjacent the panel 55.

In operation, the arms 44 of the clamps38 are pivoted in a clockwise direction of Figure 2 about the central longitudinal axes of the bolts 43 and the jig 10 located so that the outer surface 29 of the location pad 27 engages corresponding surfaces of a rail (not shown) to be provided with apertures for receiving a fishplate, the surfaces being a lower surface of an upper flange of the rail and an upper surface of a lower flange of the rail and an adjacent surface of a vertical web of the rail between the upper and lower flanges thereof. The arms 44 then are pivoted about the axes of the bolts 43 in an anti-clockwise direction of Figure 2 so that the arms 44 are positioned as shown in Figure 2.The rods 46 of the clamps 38 are then turned on their central longitudinal axes relative to the arms 44 by means of the operating handles 47 so that the flat surfaces 48 of the rods 46 engage an opposite facing surface of the vertical web of the rail remote from the surface engaged by the location pad 27. The jig 10 is thereby firmly mounted on the rail at a selected location longitudinally of the rail.

The profile of the location pad 27 is determined so as to engage a predetermined cross section of the rail to be engaged by the jig 10 and so as to provide a predetermined location in a vertical direction of the web of the rail for the apertures 23 to 26 of the plate 11.

The cutting tool having the locating device 51 attached thereto then is positioned so that the notches 58 in the side webs 53,54 of the cowl 52 receive an upper portion of the plate 11 and the locating pin 57 is received in a selected one of the notches 18 to 21. The tool then is pivoted so that an electromagnet of the tool moves towards the front surface 12 of the plate 11 and thereby becomes magnetically attached to the plate ll.

The arrangement is such that, when the cutting unit is so mounted with the locating pin 57 received in a notch 18 to 21 of the plate ll, a central longitudinal axis of the cutting member is coaxial with a central longitudinal axis of a corresponding one of the apertures 23 to 26 located below the selected notch 18 to 21. The tool is then operated so that the cutting member extends through the selected aperture 23 to 26 and cuts an aperture in the rail.

Subsequently, the tool is removed and the locating pin 57 is positioned in a another notch 18 to 21 of the plate 11 and the process is repeated until four apertures are provided in the rail. The clamps are then released and the jig 10 is moved to another location when the process is repeated.

When it is required to provide apertures for mounting of fishplates adjacent end portions of rails, a pair of rails are located so that an end portion of one rail is adjacent an end portion of the other rail and the jig 10 is arranged such that the latch member 50 is located in a gap between the end portions of the two rails. The process described above is then carried out whereby two apertures are provided in end portions of the two rails.

The jig 10 is then repositioned relative to the end portion of one of the rails so that two of the apertures 18,19 or 20,21 are coaxial with the apertures in one of the rails and the cutting procedure referred to above is then effected to provide an additional two apertures in the rail. The process is then repeated with the other rail thereby providing the two rails each with a group of four apertures for attachment of fishplates thereto.

It will be appreciated that, with the jig in accordance with the present invention, there is no requirement to measure a rail for determining sequential location of apertures to be cut in the rail. Once a datum position has been determined for the jig and the jig is clamped relative to the position, the tool is sequentially mounted relative to the jig so that the locating pin 57 is sequentially located in each of the notches 18 to 21 and, when in each of the notches 18 to 21 and the electromagnet of the unit is in engagement with the front surface 12 of the plate 11, a central longitudinal axis of the cutting member is aligned accurately with a predetermined location for an aperture to be provided in the rail on operation of the tool.

In the embodiment shown in Figures 1 and 2 substantially the whole of the profile of the outer surface 29 of the location pad 27, when the jig 10 is in use, is in engagement with a corresponding profile of a rail with which the pad 27 is in engagement. Referring now to Figures 3 to 5 of the drawings, there is shown a location pad 59 for incorporation in the jig 10 in substitution for the pad 27. The pad 59 is similar in dimensions and cross sectional profile to the pad 27 and comprises an inner surface 60 and an outer surface 61 corresponding to the inner and outer surfaces 28 and 29 of the pad 27. The pad 59 also is provided with four apertures 62,63,64 and 65 which correspond with four similar apertures (not shown) in the pad 27 and which are located in register each with a corresponding one of the apertures 23,24,25 and 26 of the plate 11.

However, unlike the pad 27, the outer surface 61 of the pad 59 is provided with three groups of shims 66,67,68,69 and 70,71, one group 66,67 being located at one end portion of the pad 59, a second group 70,71 being located at an opposite end portion of the pad 59 and a third group 68,69 being located at an intermediate portion of the pad 59. An upper member 66,68 and 70 of each group of shims extends around an upper curved profile of the pad 59 and a lower member 67,69 and 71 of each group of shims extends around a lower curved profile of the pad 59.

In use, the effect of the shims 66 to 71 is to concentrate applied pressure of the pad 59 against a rail in the area of the shims 66 to 71 and thereby effect a more precise fit with the rail, particularly if the profile of the rail does not correspond with the profile of the outer surface of the pad due, for example, to rusting of the rail.

Claims (10)

1. A jig for supporting a cutting tool relative to a workpiece comprising a support member for mounting on the workpiece, securing means for securing the support member to the workpiece and locating means for removably locating the tool relative to the support member so that, when a cutting member of the tool is advanced towards the workpiece, the cutting member engages the workpiece at a predetermined location.

2. A jig as claimed in Claim 1 wherein there is provided a plurality of locating means spaced at predetermined distances from one another each for removably locating the tool relative to the support member whereby -the cutting member is engageable with the workpiece at a corresponding one of a plurality of locations spaced at predetermined distances one from another.

3. A jig as claimed in Claim 2 wherein there is provided a plurality of guide means each for guiding the tool at a corresponding one of said locations.

4. A jig as claimed in Claim 3 wherein each guide means is located below a corresponding one of the locating-means.

5. A jig as claimed in any one of the preceding claims wherein the support member includes a portion which is elongate and in transverse cross section is adapted to engage upper and lower flanges of a rail of substantially < shape transverse cross section.

6. A jig as claimed in Claim 5 wherein the support member includes a portion which extends upwardly from the elongate portion.

7. A jig as claimed in Claim 6 wherein the upwardly extending portion comprises a plurality of recesses each for removably receiving therein a locating member of the tool.

8. A jig as claimed in Claim 7 wherein at least part of the upwardly extending portion is of magnetically attractive material.

9. A jig as claimed in any one of the preceding claims wherein a surface of the support member comprises a plurality of raised portions each for engaging corresponding portions of a surface of the workpiece.

10. A jig for supporting a cutting tool relative to a workpiece substantially as hereinbefore described and as illustrated in Figures 1 and 2 or Figures 3 to 5 of the accompanying drawings.