GB2103127A - Machining tool, e.g, drill, positioning devices - Google Patents

Abstract

A device for locating a machining tool with its axis substantially normal to the surface of a workpiece having a planar or curved profile includes a platform member 16 having first and second location means 19, 20 spaced to each side of said selected axis, so that in use the selected axis lies normal to the region of the surface to be drilled. <IMAGE>

Description

SPECIFICATION Machining tool positioning devices This invention relates to machining tool positioning devices which positively locate a machining tool with its operating axis substantially normal to the surface of a workpiece having a planar or curved profile, prior to the machining operation. By the term "machining tool" is meant a tool which performs a machining operation on a workpiece, for example a drilling, countersinking, reaming or boring operation, along a predetermined operating axis.

According to this invention, there is provided a machining tool positioning device for positioning a machining tool with its operating axis substantially normal to the surface of a workpiece having a generally planar or part-circular profile, which device includes a platform member having means to maintain the machining tool with its operating axis in aligment with a selected axis on the platform member, and first and second foot means each depending from said platform member at positions spaced to either side of said selected axis, whereby in use said selected axis lies normal to the curved surface to be machined.

Preferably, the first and second foot means are equi-spaced about said selected axis and depend from said platform member by equal distances.

The device preferably includes a clamping device operable to draw the platform member towards the surface thereby to ensure rigid location of the platform member on a workpiece.

The clamping device may include fluid-operable ram means to effect operation of the clamping device.

Where the device is to be used in conjunction with a drill for drilling a series of holes on a curved workpiece, the clamping device conveniently includes a clamping member co-operable with a previously-drilled hole in the workpiece to effect clamping. In this case the separation between the clamping member and the selected axis is advantageously adjustable to suit various pitches of holes.

Moreover, the clamping member is preferably mounted in a bearing arrangmentwhich allows swiveling movement thereof to suit various curvatures of workpiece.

By way of example only, one specific embodiment of this invention will now be described in detail, reference being made to the accompanying drawings, in which: Figure lisa top plan view of a drill to which a machining tool positioning device of the invention has been attached; Figure 2 is a view on lines Il-I I of Figure 1 but with certain parts removed for clarity; Figure 3 is a detailed plan view of the platform member of a machining tool positioning device; Figure 4 is a side view of the platform member of Figure 3; and Figure 5 is a detailed view on an enlarged scale of a collet/mandrel assembly for use on the arrangement of Figures 1 to 4.

The embodiment of device illustrated is for use with a drill of the type including a drill spindle housing which surrounds the drill spindle and is retractable against a spring bias into the drill body, and a feed cylinder which may be extended or retracted into the drill body by means of an actuator within the body. The drill is therefore of the Spacematic M62 type.

Referring to the drawings, there is shown a drill 10 of the type described to which is attached a drill positioning device 11. The drill positioning device comprises a platform member 1 6 which includes brackets 12 and 13 having bores 17, 18 which are attached to the drill spindle housing 14 and the feed cylinder 1 5 respectively of the drill 10. A pair of location feet 19, 20 project from the side of the platform remote from the drill 10. The feet are equispaced about the drill spindle housing 14, and each projects from the platform member 16 by a similar amount. A slot 21 is provided intermediate the bore 17 and foot 20. A pneumatically-operated actuation device 22 is mounted on the platform by means of three pillars 23, remote from the drill 10.

The piston rod 24 of the actuator device pivotally carries a crank arm 25, the crank arm 25 itself pivotally carrying a collet/mandrel housing member 26. The housing member carries a collet/mandrel assembly 27/28 in a spherical bearing arrangement for swivelling movement.

The mandrel 28 is secured to the inner part of the bearing arrangement, and the collet is located in slot 21 by means of a sleeve member 29 for sliding movement therealong. The position of the coliet/mandrel assembly 27/28 with respect to the slot may be varied by turning crank arm 25.

Instead of the collet/mandrel assembly 27/28, alternative forms of location and clamping devices may be used, for example those similar in operation to the clip marketed under the trade name "Avdel" by Aviation Developments Ltd.

In addition, the spherical bearing arrangement may be replaced by a rigid fixture where the curvature of the surfaces to be drilled allows.

The above-described device is designed specifically for use in applications where a template is employed to drill a series of holes along a component having a substantially circularly-curved profile. In use, the free end of the collet/mandrel assembly 27/28 is passed through a previously-drilled hole, and the drill aligned with the hole to be drilled by means of the template.

The pneumatically-operated actuation device is then operated to draw the piston rod 24, together with the crank arm 25, and the collet/mandrel housing member 26 away from the platform member 16, thereby to cause the collet 27 to expand and grip the previously-drilled hole and to draw the platform firmly against the component to be drilled, supported by the feet 1 9, 20. In this state, since the component has a part-circular profile, the platform will be in a plane parallel to that plane tangential to the surface to be drilled, and the drill spindle thus will be normal to that surface. Once the hole has been drilled, the pneumatically-operated actuation device is operated to extend piston rod 24, thus causing collet 27 to contract, thereby allowing the collet to be withdrawn from the previously-drilled hole and positioned in the hole just drilled.

The postion of the collet/mandrel 27/28 within slot 21 may be adjusted by rotating crank arm 25 about piston rod 24, thus allowing the drill positioning device to be present for various different pitches of holes to be drilled.

The spherical bearing arrangement allows the collet/mandrel assembly 27/28 to align itself substantially normal to the region of the component which it clamps.

In addition to drawing the platform to the surface of the component to be drilled, the collet/mandrel assembly serves a further purpose when the drill positioning device is used to drill a single hole through two adjacent members, for example an aircraft skin and a former element. In this instance, the collet/mandrel assembly also serves to clamp the two members together.

The above-described embodiment may be employed to drill and countersink holes in planar, conic, double curvature, concave and convex surfaces.

Claims (8)

1. A machining tool positioning device for positioning a machining tool with its operating axis substantially normal to the surface of a workpiece having a generally planar or partcircular profile, which device includes a platform member having means to maintain the machining tool with its operating axis in alignment with a selected axis on the platform member and first and second foot means each depending from said platform member at positions spaced to either side of said selected axis whereby in use said selected axis lies normal to the curved surface to be machined.

2. A device according to Claim 1. wherein the first and second foot means are equi-spaced about said selected axis and depend from said platform member by equal distances.

3. A device according to Claim 1 or Claim 2, which includes a clamping device operable to draw the platform member towards the surface.

4. A device according to Claim 3, adapted for use with a drill, wherein the clamping device includes a clamping member co-operable with a previously drilled hole in the workpiece to effect clamping.

5. A device according to Claim 4, wherein the separation between the clamping member and the selected axis is adjustable.

6. A device according to Claim 3, wherein the clamping member is mounted in a bearing arrangement which allows swivelling movement thereof.

7. A device according to any of Claims 3 to 6, which includes fluid-operated ram means to effect operation of the clamping device.

8. A device substantially as hereinbefore described, with reference to and as illustrated in, any of the accompanying drawings.