GB2250224A

GB2250224A - Device for locating a tool on a workpiece

Info

Publication number: GB2250224A
Application number: GB9025944A
Authority: GB
Inventors: Ming-Tang Chen
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-11-29
Filing date: 1990-11-29
Publication date: 1992-06-03
Also published as: GB9025944D0

Abstract

The device comprises cursor means (4) arranged to receive a tool, e.g. a drill jig, to be located in a desired position with respect to a workpiece and reference means (6) connected adjustably to said cursor means (4), wherein said cursor means (4) and said reference means (6) are movable relative to each other to effect said adjustment therebetween to determine the reference coordinates of the desired position with respect to the workpiece and said reference means (6) is arranged to engage the workpiece to locate said cursor means (4) in that desired position. The reference means comprises two pairs of elongate measuring racks (6), the racks (6) in each pair being parallel to each other and perpendicular to the racks (6) in the other pair. The measuring racks (6) are movable reciprocably into and out of engagement with respect to associated gears of the cursor means (4). The cursor means (4) can support twin columns for a drill, or a saw with associated workpiece rests mounted on the racks. <IMAGE>

Description

TOOL LOCATING DEVICE DESCRIPTION This invention relates to a device for locating a tool in a desired position on a workpiece and relates especially, but not exclusively, to such a device for such location of a drill with respect to a workpiece for drilling a hole therein.

In order to drill a hole in a workpiece in a desired position with respect thereto, it is generally necessary to refer to an engineering drawing or blueprint of the workpiece and to transfer the coordinates (abcissa and ordinate) of the desired position of the hole from the drawing or blueprint to the workpiece by drawing respective abscissa and ordinate lines thereon, thereby determining that position. This method is considered to be generally inconvenient and to take a comparatively long time.

It is an object of the present invention to provide a device for locating a tool, such as, a drill, in a desired position with respect to a workpiece, which overcomes, or at least substantially reduces, the disadvantages associated with known tool positioning methods and, in particular, provides a device which: 1. eliminates the need to draw positional abscissa and ordinate (coordinates) on the workpiece in accordance with an engineering drawing or blue print of the workpiece; 2. reduces the amount of time in determining the desired position for the tool; and 3. permits the tool to be used almost immediately the desired position on the workpiece has been determined.

Accordingly, the invention provides a device for locating a tool in a desired position with respect to a workpiece, comprising cursor means arranged to receive a tool to be located in a desired position with respect to a workpiece and reference means connected adjustably to said cursor means, wherein said cursor means and said reference means are movable relative to each other to effect said adjustment therebetween and to determine the reference coordinates of the desired position with respect to the workpiece and said reference means is arranged to engage the workpiece to locate said cursor means, and hence any associated tool, in that desired position.

Preferably, said reference means comprises two pairs of graduated measuring racks for determining respective coordinates of the desired position with respect to the workpiece, the racks in each pair being parallel to each other and perpendicular to the racks in the other pair. Also, each rack can have at an end thereof an element, preferably in the form of a rotatable tab, for engaging the workpiece, preferably an associated edge thereof.

In a preferred embodiment, the cursor means comprises a generally circular support body with upper and lower toothed gears engageable by respective pairs of racks, the racks of each pair thereof being arranged on diametrically opposed sides of the associated gear.

Means may be provided to bring each measuring rack into and out of engagement with its associated gear for adjustment purposes, with the preferred embodiment having cursor means including a base plate with a pair of guide grooves on diametrically opposed sides of the lower gear, the support body having a pair of guide grooves on diametrically opposed sides of the upper gear and each rack being slidably mounted in a support bracket which is received in a respective one of the grooves for reciprocable slidable movement therealong, to bring the rack into and out of engagement with the associated gear. Preferably, each rack support bracket is generally U-shaped and reciprocably slidably movable along its associated guide groove by means of a rotatable screw drive which is connected to the base of the generally U-shaped bracket and is threaded through a fixed element.

The upper and lower gears and intermediate support body, together with a cover plate, may be provided with respective central openings which are arranged coaxially of each other and through which a central, hollow cylindrical axle extends, with the lower end of the axle engaging the base plate and its central bore overlying a central opening in that plate. The upper end of the axle may be threaded to receive a lock nut.

In order that the invention may be more fully understood, a preferred embodiment of tool locating device in accordance therewith will now be described by way of example and with reference to the accompanying drawings in which: Figure 1 is a perspective view of a preferred embodiment of tool positioning device; Figure 2 is a sectional view of the device along the line A-A in Figure 1; Figure 3 is a sectional view of the device taken along the line B-B in Figure 2; Figure 4 is a sectional view of the device taken along the line C-C in Figure 2; Figure 5 is a perspective view of a modification of the embodiments shown in Figures 1 to 4, incorporating a drill; and Figure 6 is a perspective view of another modification of the embodiment shown in Figures 1 to 4, incorporating a saw.

Referring firstly to Figures 1 and 2 of the accompanying drawings, a device for locating a tool in a desired positionwith respect to a generally planar workpiece in the form of a drill jig consists of cursor means having a generally circular support body 4, 'a circular cover plate 8, an upper gear 5 located between the body and cover plate, a circular base plate 2 and a lower gear 3 located between the body and base plate.

Such components are arranged coaxially of each other, with a hollow cylindrical axle 1 extending through respective coaxial holes in the cover plate 8, upper gear 5, support body 4 and lower gear 3 and engaging the base plate 2 and with the bore coaxial of the axle 1 in register with a central opening 10 in the base plate. The upper end of the hollow cylindrical axle 1 is threaded and receives a correspondingly-threaded lock nut 9. As can be seen from Figure 2, these components are assembled in a coaxial, symmetrical manner with respect to each other.

Reference means comprising a first pair of graduated, measuring racks 6 associated with the cursor means, are arranged on respective, diametrically opposed sides of the upper gear 5, with their respective sets of teeth engaging that upper gear.

Similarly, a second pair of graduated, measuring racks 6 associated with the jig, are arranged on respective, diametrically opposed sides of the lower gear 3, with their respective sets of teeth engaging that lower gear. The upper and lower pairs of measuring racks 6 are arranged perpendicularly with respect to each other, thereby constituting respective abscissa (xcoordinate) and ordinate (y-coordinate) reference lines for the drill jig.

At opposed ends of the measuring racks 6 in each pair thereof, are provided rotatable tabs 20 for engaging respective edges or other suitable parts of an associated workpiece.

As shown in Figures 3 and 4, which are respective sections along the lines B-B and C-C in Figure 2, each pair of graduated, measuring racks 6 is provided with a pair of rack support brackets 7 each comprising a generally U-shaped support 22 with a flute 21 in each arm thereof in which the associated rack 6 is received for slidable movement with respect thereto. Each Ushaped rack support 22 is movable reciprocably in a guide groove 11, the pair of guide grooves 11 for the corresponding pair of brackets 7 for the upper pair of racks 6 being in diametrically opposed positions in the upper surface of the circular support body 4.

Similarly, the diametrically opposed pair of guide grooves 11 for the corresponding pair of U-shaped supports 22 for the lower pair of measuring racks 6 are formed in the upper surface of the circular base plate 2.

Each support 22 is movable reciprocably in its guide groove 11 to bring its associated graduated measuring rack 6 in to and out of engagement with the corresponding upper or lower gear 5, 3 by means of a screw drive 7 which is connected to the base of the Ushaped support 22, is threaded through a fixed element 12 and is rotatable by a crank 24. The lower portion of the hollow cylindrical axle 1 is received in the axial hole 14 in the lower gear 3 which is freely rotatable with respect to the axle 1 when the gear teeth are in engagement with the rack teeth 13 and when the rack 6 is moved linearly to rotate the gear 3. A similar arrangement exists in respect of an upper portion of the axle 1, the upper gear 5 and associated racks 6.

Also, the support body 4 is provided with upper and lower central recesses 16 in which are received respective central extensions 15 of the upper and lower gears 5, 3. This arrangement retains the said components of the jig in position radially with respect to each other.

Respective holes 25 (Figure 1) and passages 17 are provided in the cover plate 8 and support body 4, so that a graduated scale 18 on each of the lower pair of measuring racks 6 can be viewed through the jig.

Thus, it can be seen that the drill jig comprises two pairs of parallel measuring racks 6 which are arranged normally of each other and whose structures are substantially the same, as are the respective components associated therewith.

Although the tab 20 at one end of each measuring rack 6 is usually oriented to engage the respective edge of a workpiece to be drilled in a desired position thereon, it may be used alternatively to rest upon a reference point or line provided on the surface of the workpiece, for positioning the drill jig accurately with respect thereto.

When the abscissa and ordinate (x and y coordinates) for the jig with respect to a workpiece have been set at the respective values by adjusting the lengths of the corresponding racks 6 with regard to the body 4, the lock nut 9 can be screwed down to engage the cover plate 8 tightly, thereby locking the components of the jig together, such that the racks 6 cannot be moved. Any subsequent adjustment of a measuring rack 6 can be carried by loosening that lock nut 9.

In use of the preferred embodiment of drill jig described above in relation to Figures 1 to 4 of the drawings, a user who requires to determine exactly a desired position on a workpiece where a hole is to be drilled, ascertains the abscissa (x coordinate) for that position from, say, an engineering drawing of the workpiece, and then adjusts accordinglythe length of each of the pair of upper measuring racks 6 with respect to the body 4. Similarly, the ordinate (y coordinate) of the required position is set by adjusting accordingly each of the lower pair of racks 6 with respect to the body 4.

Such adjustment of the upper and lower pairs of abscissa and ordinate racks 6 may be carried out with or without respective ones being in engagement with the corresponding upper or lower gear 5, 3 depending on circumstances. Subsequently, the rotatable tabs 20, which are now set at the correct spacing defined between respective opposed edges or other reference positions of the workpiece, are then placed into engagement therewith, with the bore of the hollow cylindrical axle 1 and the central hole 10 in the base plate 2 overlying the desired position on the workpiece to be drilled.

Alternatively, the tabs 20 can be brought into engagement initially with respective pairs of opposed edges or other reference positions of the workpiece after releasing, where necessary, respective racks 6 from engagement with the upper and lower gears 5, 3.

Then, when those racks 6 have been brought back into engagement with the gears 5, 3, the body 4, and associated components of the jig, can be moved, firstly, with respect to the upper pair of measuring racks 6 in engagement with the upper gear 5 until the required abscissa is located, such location being determined by viewing through respective holes 25 in the cover plate 8 to observe locating pointers (not shown) lying in register with the required position on the graduated scales 18 of the pair of upper racks 6.

In a similar manner, the required ordinate is determined by moving the body 4, and associated components of the jig, with respect to the pair of lower racks 6. Then, the lock nut 9 can be screwed down on to the cover plate 8, to lock the jig in the desired position with respect to the workpiece.

Subsequently, a drill can be inserted through the centre hole of the lock nut 9, the axial bore of the axle 1 and the central hole 10 in the base plate 2, for drilling a hole in the desired position in the workpiece.

Thus, the need to draw lines or other reference means upon the workpiece to determine the correct position for drilling is eliminated.

To determine the centre point of, say, a generally planar, rectangular workpiece, the respective pairs of racks 6 are adjusted such that the racks of each pair extend by the same amount on either side of the jig body 4 with the corresponding tabs 20 engaging the associated edges of the workpiece. In this manner also, the two centre lines of the workpiece can be determined.

Referring now to Figure 5 of the drawings, a modified form of the embodiment described above in relation to Figures 1 to 4 of the drawings is shown, comprising substantially the same drill jig components but including two support columns 26, 27 extending upwardly from the cover plate 8 perpendicular thereto.

The two colums lie on a centre line defined between the upper pair of graduated, measuring racks. The two columns 26, 27 are located within respective helical compression springs 28, 29 and a mount 31 carries a portable electrical drill lying on the extended centre line of the bore of the axle 1 of the jig. With this arrangement, the drill 30 can be used to drill a hole in a workpiece, once the jig has been positioned correctly with respect thereto, as described above in relation to the embodiment of Figures 1 to 4.

Also, the cover plate 8 is provided with an angular scale in degrees.

Turning finally to Figure 6 of the drawings, another modified form of embodiment comprises substantially the same components as the two embodiments described above in relation to Figures 1 to 4 and Figure 5, although in this case a saw 35 is mounted upon the cover plate 8 by means of the pair of diametrically opposed columns 26, 27 and respective mounting means 33, 34 located on those columns.

Two blocks 36 for holding the lower pair of measuring racks 6 are used to stabilise the workpiece in preparation for its being sawed. The cover plate 8 can be turned to a predetermined angle using the degree scale thereon, such that the workpiece can be sawed to any desired angle of cut or other specification.

Claims

1. A device for locating a tool in a desired position with respect to a workpiece, comprising cursor means arranged to receive a tool to be located in a desired position with respect to a workpiece and reference means connected adjustably to said cursor means, wherein said cursor means and said reference means are movable relative to each other to effect said adjustment therebetween to determine the reference coordinates of the desired position with respect to the workpiece and said reference means is arranged to engage the workpiece to locate said cursor means, and hence any associated tool, in that desired position.

2. A device according to claim 1, wherein said reference means comprises two pairs of graduated measuring racks for determining respective coordinates of the desired position with respect to the workpiece, the racks in each pair being parallel to each other and perpendicular to the racks in the other pair.

3. A device according to claim 3, wherein each rack has at an end thereof an element, preferably in the form of a rotatable tab, for engaging the workpiece, preferably an associated edge thereof.

4. A device according to claim 2 or 3, wherein said cursor means comprises a generally circular support body with upper and lower toothed gears engageable by respective pairs of the measuring racks, the racks of each pair thereof being arranged on diametrically opposed sides of the associated gear.

5. A device according to claim 4 including means arranged to bring each measuring rack into an out of engagement with its associated gear.

6. A device according to claim 4 or 5, wherein said cursor means includes a base plate having a pair of guide grooves on diametrically opposed sides of the lower gear, wherein the support body has a pair of guide grooves on diametrically opposed sides of the upper gear and wherein each rack is slidably mounted in a support bracket which is received in a respective one of the grooves for reciprocal slidable movement therealong, to bring the rack into and out of engagement with the associated gear.

7. A device according to claim 6, wherein each rack support bracket is generally U-shaped and is reciprocably slidably movable along its associated guide groove by means of a rotatable screw drive which is connected to the base of the generally U-shaped bracket and is threaded through a fixed element.

8. A device according to claim 6 or 7, wherein the upper and lower gears and intermediate support body, together with a cover plate, have respective central openings which are arranged coaxially of each other and through which a hollow cylindrical axle extends, with the lower end of the axle engaging the base plate, with the bore of the axle in register with a central opening in the base plate.

9. A device according to claim 8, wherein the upper end of the axle is threaded and receives a lock nut thereon.

10. A device according to any of claims 4 to 9, wherein each of the upper and lower gears has a central extension received in respective, opposed central recesses in the support body.

11. A device according to any of claims 2 to 10, wherein said cursor means includes respective holes therein, through which locating pointers lying in register with the required position on the respective measuring racks, can be viewed.

12. A device according to any of claims 8 to 11, wherein the upper surface of the cover plate has an angular scale.

13. A device according to any preceding claim in the form of a drill jig.

14. A device according to any preceding claim including a drill mounted on said cursor means upon two support columns for reciprocal vertical movement with respect thereto, such that the drill can extend through the central axis of said cursor means to drill a hole in a workpiece when the device has been located in the desired position.

15. A device according to claim 14, wherein the drill is spring-mounted upon the support columns.

16. A device according to zany of claims 1 to 12, including a mount for supporting a saw thereon at any preset angle with respect to said cursor means.

17. A device for locating a tool in a desired position with respect to a workpiece substantially as hereinbefore described with reference to Figures 1 to 4, Figure 5 or Figure 6 of the accompanying drawings.