GB2102712A - Machine tool which can be driven by an electrically powered hand tool - Google Patents

Abstract

A machine tool having an abrasive endless belt (13) which extends around a drive roller (11) and a driven roller (12) mounted for rotation in a frame portion (10a) of a frame (10), said frame (10) having a frame portion (10b) provided with a mounting plate (27) on which is mounted an electric drill (28) whose chuck (33) engages a drive shaft (14) for driving the drive roller (11). The machine tool can be clamped in alternative positions by a clamp (34) to a support so that the belt (13) either extends horizontally or vertically or the machine tool can be inverted and provided with a handle (36) so as to be used as a mobile sander. An attachment may be fitted to enable the grinding of valves of an internal combustion engine. <IMAGE>

Description

SPECIFICATION Machine tool which can be driven by an electrically powered hand tool This invention relates to a machine tool having an abrasive endless belt for carrying out work on a workpiece. Such a machine may be used to effect a linishing or sanding or polishing or de-burring or grinding operation.

Such machine tools are known in industry and they are provided with a built-in electric motor and with a fence or table against which the workpiece is held. Such machines are heavy and are not portable in the sense that they can not be easily lifted manually and carried from a storage position to a position of use on a work bench. Usually such machine tools are permanently bolted to a work bench or table.

The average model maker or engineer would like to have such a machine tool at his or her disposal but the high cost of such a machine tool provided with its own electric motor are prohibitive and such machine tools, when permanently fixed to a work bench or table, take up a great deal of useful work space. Such machine tools can not be mounted in differently orientated positions not used as a movable hand tool.

According to the present invention there is provided a machine tool having an abrasive endless belt for carrying out work on a workpiece, comprising a frame having a first portion in which are mounted a drive roller and a driven roller about which said endless belt extends and a second portion provided with means for mounting thereon an electrically powered hand tool for driving the driven roller, said second portion being capable of being clamped to a support surface in alternative positions such that the belt is either horizontal or vertical.

An embodiment of the invention will now be described, by way of an example, with reference to the accompanying drawings, in which Figure 1 is a perspective view of a machine tool according to the present invention, partly in section and partly in exploded view, Figure 2 is a perspective view of the machine tool showing an electric drill attached thereto for driving the machine tool, Figure 3 is a perspective view showing the machine tool vertically mounted, Figure 4 is a perspective view showing the machine tool inverted for use as a mobile sander, and Figure 5 is a perspective view of a valve grinding attachment fitted to the machine tool.

The machine tool comprises a frame 10 having a portiion 1 0a and a portion 1 Ob. The portion 1 0a is of substantially inverted chan nel section in transverse cross-section.

Mounted at one end of the portion 1 Oa is a drive roller 11 and mounted at the other end of the portion 1 0b is a driven roller 12.

Extending around the rollers 11 and 12 is an endless abrasive belt 13. The drive roller 11 is mounted on a drive shaft or spindle 14 which extends through bearings 15 provided on the frame portion 1 0a and the drive roller 11 is secured to the shaft or spindle 14 by a set-screw 16. The driven roller 12 is rotatably mounted on bearings on a spindle 17 which extends through slots 18 provided in the side walls of the frame portion 1 ova. Each end of the spindle 17 is provided with an adjustment screw 19 which passes through a hole in an adjustment rod 20 fixed to the frame portion 1 ova. In screw-threaded engagement with each adjustment screw 19 are locknuts 21.

Mounted on the frame portion 1 0a by a screw 22 is a fence 23 which extends over the upper run of the abrasive belt 13. The fence 23 can be moved into a desired angular position by slackening the screw 22 and then clamped in the desired angular position by tightening the screw 22. The frame portion 1 0a is provided with holes 24 enabling the fence 23 to be mounted thereon in an alternative position as indicated by the broken lines at 23a.

The portion 1 0b of the frame 10 has side walls 25 which extend at right angles to the portion 10a, a base portion 26 and an end wall 27 which constitutes a suport plate for an electric portable drill 28 which can be attached to the machine tool for driving same.

The end wall 27 is provided with a circular opening 29. A screw-threaded hole 30 communicates with the opening 29 and a grubscrew 31 is received in the screw-threaded hole 30. Received in the circular opening 29 is an adaptor bush 32 which can be chosen from three adaptor bushes 32 having different internal diameters. The bushes 32 are preferably formed of plastics material and the one that has a good fit on the spigot of the drill 28 is the one which is used.

In order to fit the electric drill 28 to the machine tool the chosen bush 32 is fitted to the spigot of the drill 28 and the drill chuck 33 is opened to accept the drive shaft or spindle 14. The chuck part of the drill 28 is passed through the opening 29 and the bush 32 is fully located in the opening 29. The grub-screw 31 is then tightened to hold the drill 28 firmly in the end wall 27. The setscrew 16 is loosened and the drive shaft or spindle 14 is moved into the open chuck 33 as far as it will go and the chuck 33 is then tightened. The drive roller 11 is adjusted so that its ends are clear of the side walls of the frame portion 1 0a and the set-screw 16 is tightened. The abrasive belt 13 is then pushed over the rollers 11 and 12 with the fence 23 removed.The driven roller 12 is then adjusted by adjusting the position of the locknuts 21 on the adjustment screws 19 to take up slack in the belt 13. By such adjustment the position of the driven roller 12 can be adjusted so as to ensure that the belt 13 will run evenly in the centre of the frame portion 1 ova. The adjustable fence 23 is then fitted in either of its alternative positions.

A G-clamp 34 is provided for clamping the machine tool to a work bench or table. One limb of the clamp 34 extends through an opening 35 provided in one of the side walls 25. In this clamped position, as shown in Figs. 1 and 2, the abrasive belt 13 extends horizontally. Alternatively the machine tool can be clamped in a vertical position as shown in Fig. 3. If desired the fence 23 can be dispensed with when the machine tool is in a vertical position and be replaced by a work table which is larger than the fence 23 and which also can be angularly adjustable.

The upper edges of the side walls 25 and end wall 27 are located below the upper surface of the frame portion 1 0a so that the machine tool can be inverted and used as a portable sanding unit as shown in Fig. 4. In this case the fence 23 is removed and a handle 36 is attached to the frame portion 10b.

It will be appreciated that many different types of accessories can be fitted to the frame 10. For example, an attachment can be fitted to enable valves of internal combustion engines to be ground by the abrasive belt 13, as shown in Fig. 5. The valve grinding attachment is fitted with the fence 23 removed and it consists of a mounting bracket 37 which is secured by bolts 38 to the side of the frame portion 10a, the bracket 37 having transversely extending walls 39 between which is located a block 40 having a Vshaped groove 41 in its upper surface.

Mounted in the block 40 and extending from one end thereof is a stop rod 42 which can be clamped by a grub screw (not shown) provided in the underside of the block 40. In screw-threaded engagement with the stop rod 42 is a screw 43. Pivotably mounted on the walls 39 by means of a pivot bolt 44 is a channel section member 45 through the base of which extends two screw-threaded spring loaded plungers 46 provided with lock-nuts 47. The valve is shown at 48.

The valve grinding attachment is used as follows:- The lock-nuts 47 are slackened and the two plungers 46 are unscrewed to allow the stern of the valve 48 to be fitted into the groove 41 of the block 40. The stem is lightly oiled or greased before fitting. The two plungers 46 are then tightened onto the stem of the valve 48 and then unscrewed a half to three quarters of a turn and the lock-nuts 47 tightened.

The grub screw in the underside of the block 40 is slackened and the screw 43 turned to allow equal amounts of the thread on each side of the upturned end of the rod 42. The valve is positioned with the valve face just clear of the belt 13 and held in this position and the stop rod 42 is pushed into the block 40 until the screw 43 makes contact with the end of the valve stem. The grub screw is then tightened to clamp the stood rod 42.

The drill is then operated to drive the belt 13 and light pressure is applied to the centre of the valve head by the end of a file handle or screwdriver or any other suitable means and the screw 43 which is in contact with the end of the valve stem is gently unscrewed thus bringing the valve head into contact with the belt 13 causing the valve 48 to revolve.

The belt 13 will continue to grind the valve head until unscrewing of the screw 43 is ceased. As soon as sufficient metal has been removed and before grinding has finished the screw 47 is given a quick turn forward to lift the valve head from the belt 13. This avoids leaving a flat on the ground face.

Any slight alteration to the grinding angle on the face of the valve can be made by slackening off the pivot bolt 44, adjusting angular position of the block 40 and member 45 and re-clamping the pivot bolt 44.

In order to change the belt 13 the fence 23 is removed and the position of the driven roller 1 2 adjusted to slacken the belt 13 which can then be slid off the rollers 11 and 12.

When the machine tool is not in use the electric drill 28 can be removed simply by opening the chuck 33, slackening the grubscrew 31 and withdrawing the drill 28 with the bush 32 from the opening 29. The drill 28 can then be used for other purposes and the machine tool can be stored under the bench or in another convenient place. The machine tool is relatively light in weight and can be easily lifted manually.

Such a machine tool can be provided with a grade of belt 13 which will not only polish and shape metal and wood but can be used for sharpening cutlery, chisels, drills and other cutting blades. The belt 13 can be used for shaping ceramics, plastics material, rubber etc.

Claims (12)

1. A machine tool having an abrasive endless belt for carrying out work on a workpiece, comprising a frame having a first portion in which are mounted a drive roller and a driven roller about which said endless belt extends and a second portion provided with means for mounting thereon an electrically powered hand tool for driving the drive roller, said second portion being capable of being clamped to a support surface in alternative positions such that the belt is either horizontal or vertical.

2. A machine tool as claimed in claim 1, in which said first frame portion is substan tially channel section in transverse cross-section and said second portion extends substantailly at right angles to the first frame portion and has an end wall provided with an opening in which a said electically powered hand tool can be clamped and engaged with a drive shaft or spindle of the drive roller.

3. A machine tool as claimed in claim 1 or claim 2, in which the driven roller is adjustable in position for tensioning the abrasive belt and for ensuring that in use the belt runs true.

4. A machine tool as claimed in any preceding claim, in which the upper edges of the second portion of the frame are located below the level of the upper surface of the first portion of the frame.

5. A machine tool as claimed in any preceding claim provided with an angularly adjustable fence or table.

6. A machine tool as claimed in claim 5, in which the fence or table can be mounted in alternative positions on the first portion of the frame.

7. A machine tool as claimed in any preceding claim, in which the means for mounting an electrically powered hand tool on said second portion of the frame comprises a mounting plate forming part of said second portion and having therein a circular opening, a bush mountable on the electrically powered hand tool and receivable in said opening, and a screw which extends into the opening for clamping the bush to the mounting plate.

8. A machine tool as claimed in any preceding claim, in which the drive roller is mounted on a drive shaft which can be moved axially in mounting bearings, and means for clamping the drive roller to the drive shaft.

9. A machine tool as claimed in any preceding claim, provided with a clamp device for clamping said second portion of the frame to a support surface.

10. A machine tool as claimed in any one of claims 1 to 4 or claim 7 or claim 8 when dependent upon any of claims 1 to 4, in which the frame is provided with a handle to enable the machine tool to be used as a portable sander.

11. A machine tool as claimed in any one of claims 1 to 4, provided with an attachment for grinding valves.

12. A machine tool having an abrasive endless belt for carrying out work on a workpiece substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.