GB2355649A

GB2355649A - Machine for performing generally parallel operation on an object

Info

Publication number: GB2355649A
Application number: GB9925155A
Authority: GB
Inventors: Brian David Reeks; Colin Derek Charles; Howard James Goddard
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-10-26
Filing date: 1999-10-26
Publication date: 2001-05-02
Also published as: GB9925155D0

Abstract

A machine 10 for performing a motional operation such as brushing, polishing, buffing, abrading, or cutting an object comprises: a body 12, first and second operating elements 22a,22b for engaging the object and mounted for generally mutually parallel reciprocating motion with respect to each other and the body; and a drive mechanism (see figure 3). The drive mechanism reciprocates the operating elements in an out of phase manner with respect to each other, where the motion may be simple harmonic. The operating elements may be formed of groups of elements, ie. 22a,22c and 22b,22d, and the out of phase reciprocating motion is intended to reduce run-away and vibration of the machine. There may be a third operating element which also reciprocates in an out of phase manner with respect to the first two elements (see figure 5).

Description

2355649 TITLE Machines for Performing Motional Operations on Objects, such

as Brushing, Polishing and Cutting.

DESCRIPTION

This invention relates to machines for performing motional operations on objects. Although the invention was originally conceived as a shoe brushing machine, it is also applicable to other operations on other objects, such as brushing, polishing, buffing, abrading and cutting of objects in general.

Static and hand-held shoe brushing machines are known in which a brush wheel is rotated by an electric motor and is applied to the shoe to brush it. A problem with such machines, especially of the hand-held type, is that, due to the revolving motion, the brush wheel tends to run away across the surface of the shoe. Buffing and sanding machines are also known in which a buffing mop or sanding disc is mounted on a revolving backing disc. These also suffer from the run-away problem and, in the case of a sanding machine, cannot be used satisfactorily as a finishing sander for wood because it is not possible to sand solely with the grain of the wood. Orbital sanders do not suffer from the run-away problem, but again they cannot be used satisfactorily as a finishing sander for wood. On the contrary, belt sanders can be used for finishing, but they do suffer from the runaway problem. Hand- held hedge trimmers and electric carving knives are also known in which a first, serrated blade is reciprocated alongside a second, serrated blade which is fixed with respect to the body of the trimmer or knife. These machines suffer from vibration when unloaded due to the reciprocating mass of the first blade, and suffer from vibration even more when under load as the second fixed blade cuts into the workpiece.

The present invention, or at least specific embodiments of it, are concerned with alleviating the above-mentioned problems.

In accordance with the present invention, there is provided a machine for performing a motional operation on an object, the machine comprising: a body, first and second operating elements for engaging the object and mounted for generally mutually- parallel reciprocating motion with respect to the body, and a drive mechanism for reciprocating the operating elements with respect to the body and out of phase with respect to each other. As a result of the reciprocating motion, run-away is not a problem, and the machine can be u'sed as a finishing sander for wood. As a result of both operating elements reciprocating out of phase with each other, it can be arranged that there is little or no vibration, whether unloaded or under load.

Preferably, the first operating element is one of a first group of such operating elements, and the drive mechanism is arranged to reciprocate the operating elements of the first group in phase with each other. As a result, it is possible to distribute more evenly the frictional forces between the operating elements and the object. The second operating element may likewise be one of a second group of such operating elements, with the drive mechanism being arranged to reciprocate the operating elements of the second group in phase with respect to each other.

In a preferred embodiment of the invention, the drive mechanism is arranged to reciprocate the first and second operating elements in anti-phase with respect to each other (i.e.

1800 out of phase).

The machine may include a third operating element for engaging the object and mounted for reciprocating motion with respect to the body generally parallel to the first and second operating elements, the drive mechanism being arranged to reciprocate the first, second and third operating elements out of phase with respect to each other (e.g. 1200 out of phase).

Preferably the surface areas of the operating elements, or the aggregate surface areas of the operating elements in the groups thereof, are generally equal. This also helps keep vibration low.

Preferably, there is an odd number of the operating elements. An odd number can be arranged to cause torsional vibrations to be kept low.

Each operating element may be a brush, or it may provide a polishing or buffing surface, or it may have an abrasive surface, or the operating elements may have complementary cutters.

Preferably, the drive mechanism is arranged to reciprocate each operating element with simple harmonic motion.

The benefits of the invention are particularly applicable in the case where the body is arranged to be held by hand.

Specific embodiments of the present invention will now be described, purely by way of example, with reference to the accompanying drawings, in which:

Figure I is an isometric view of a shoe brush which is a first embodiment of the present invention; Figure 2 is an isometric view, on a larger scale, of one end of the brush of Figure 1 with its housing removed; Figure 3 is an isometric view of the other end of the brush of Figure 1 with its housing removed; Figure 4 is a schematic under-plan view of a buffing machine which is a second embodiment of the present invention; and Figure 5 is a schematic under-plan view of a sanding machine which is a third embodiment of the present invention.

Referring to Figure 1, an electric shoe brush 10 has an elongate housing 12 of a shape and size that can be readily held in the hand, with an electrical supply lead 14 extending into one end of the housing adjacent an electrical on/off switch 16. A generally rectangular aperture 18 is formed in one face 20 of the housing 12 and four elongate, parallel brushing elements 22a-d project from the aperture 18. Each brushing element 22a-d has a back 24 and a brush of bristles 26 fixed to back 24. Each brushing element 22a-d is shorter than the length of the aperture 18. As will be described in more detail below, when the lead 14 is connected to a suitable electricity supply and the switch 16 is turned on, the first and third brushing elements 22a,c are reciprocated with simple harmonic motion in phase with each other in their longitudinal direction within the aperture 18, and the second and fourth brushing elements 22b,d are reciprocated with simple harmonic motion in phase with each other in their longitudinal direction and 1801 out of phase with the first and third brushing elements 22a,c.

Referring now also to Figures 2 and 3, inside the electric shoe brush 10, there is mounted a slideway 28 formed with four parallel elongate channels 30a-d each having grooved side walls, and an electric motor 32 mounted beneath the slideway 28. Into each channel 30a-d, an elongate slider 34a-d is fitted in easy-sliding engagement with the grooves of the sidewalls of the channel 30a-d. The sliders 34a-d project above the slideway 28, and to each of the sliders 34a-d the back 24 of a respective one of the brushing elements 22a-d is attached, preferably with releasable fastenings (not shown) so that the brushing elements 22a- d can be replaced once they have worn out.

Referring in particular to Figure 3 (which shows the driven ends of the sliders 34a-d in phantom lines), a mounting plate 34 projects from one end of the slideway 24, and a bracket 36 depends from one end of the mounting plate 34. The motor 32 has a drive shaft 38 which is journalled at its distal end in the bracket 36 and which drives a worm (not shown) on the shaft 38. The worm in turn drives a worm wheel (not shown) which is beneath the mounting plate 34 and which, in common with a first spur gear 40 above the mounting plate 34, is fixed to a shaft 42. The worm and wheel would typically provide a speed reduction of 121/2: 1 or 18: 1. The first spur gear 40 meshes with a similar second spur gear 44 mounted above the plate 34 on a stab (not shown). Each spur gear 40,44 is fitted with an upstanding peg 46,48, and the gears 40,44 are meshed such that the pegs 46,48 are 1800 out of phase, i.e. when the peg 46 is at its closest to the slideway 28, the peg 48 is at its furthest from the slideway 28. The drive mechanism also includes a pair of L-shaped drive members 50,52. The shorter arms of these members 50,52 are arranged longitudinally and are fixed to the undersides of the adjacent ends of the fourth and third sliders 34d,c, respectively. The longer arms of the members 50,52 are arranged transversely and are formed with slots 54,56 which are slidingly engaged by the pegs 46,48 on the spur gears 40,44, respectively. The distal ends of the longer arms of the members 50,52 are fitted with upstanding pegs 58,60 which engage in transverse grooves in the undersides of the adjacent ends of the second and first sliders 34b,a, respectively, the groove being shown in hidden lines and referenced 62 for the second slider 34b and not being shown for the first slider 34a.

It will be appreciated from the above that, as the drive shaft 38 of the motor 32 rotates, the L-shaped drive members 50,52 oscillate with simple harmonic motion 1801 out of phase with each other and thus drive the brushing elements 22a-d in the manner described above with reference to Figure 1. The fixing of the drive members 50,52 to the fourth and third sliders 34d,c, respectively, maintains the orientation of the drive members 50,52, and the engagement of the pegs 58,60 with the grooves 62 in the second and first sliders 34b, a, respectively, prevents the mechanism jamming should the channels 30a-d in the slideway 28 be out of true.

When the electric shoe brush 10 is being driven unloaded, or when it is loaded evenly across the four brushing elements 22a-d, it should be noted that the net mass x acceleration in the longitudinal direction of all of the parts of the brush 10 is zero, and the net frictional force in the longitudinal direction on the four brushing elements 22a-d is zero. As a result, there will be no longitudinal vibration and no tendency for the brush 10 to run away in the longitudinal direction.

It will be appreciated, however, that, viewing the brushing elements 22ad face on, they are not mirror symmetrical about the central longitudinal axis. As a result, there may be some torsional vibration about the central normal axis 64 shown in Figure 1. In order to reduce this torsional vibration, the operating elements may be rearranged as shown for the second embodiment of the invention illustrated in Figure 4.

Figure 4 shows a buffing machine 66 which, rather than having four brushing elements as in Figures 1 to 3, has three buffing pads 68a-c each of which is releasably attached to a respective backing by hook and loop fastening material. The lengths of the buffing pads 68a-c are similar, but the central buffing pad 68b is twice as wide as the outer buffing pads 68a,c. (Of course, instead of the double-width central pad 68b, two side-by-side single-width pads could be used.) The outer buffing pads 68a,c are reciprocated in phase with each other and 1801 out of phase with the central buffing pad 68b by a motor and drive mechanism similar to that described above with reference to Figures 1 to 3, but modified as necessary. It will be appreciated that, in the case of Figure 4, with even loading across the buffing pads 68a-c, the net torsion about the central normal axis 64 is zero.

Figure 5 shows a third embodiment in the form of a sanding machine 70, which differs from the buffing machine 66 of Figure 4 in the following respects. Obviously, sanding strips are used instead of buffing pads. There are five such sanding strips 72a- e. The first, second, fourth and fifth sanding strips 72a,b,d,e are of the same width, whereas the third, central sanding strip 72c has twice that width. In operation, the second and fourth strips 72b,d are reciprocated in phase with each other but + 1201 out of phase with the third strip 72c, and the first and fifth strips 72a,e are reciprocated in phase with each other but +1201 out of phase with the second and fourth strips and thus -1201 out of phase with the third strip 72c. It will be appreciated that the sanding machine 70 can be constructed so that, whether it is unloaded or evenly loaded across the sanding strips 72a-e, there is no longitudinal or torsional vibration.

Furthermore, there is no tendency for the machine 70 to run away, and it can be used as a finishing sander for wood by aligning the longitudinal direction of the machine 70 with the grain of the wood.

It will be appreciated that many modifications and developments may be made to the invention. For example, the techniques described above may be applied to hedge trimmers or electric carving or bread knives. In a simple form, such machines would have a pair of serrated blades which are mounted alongside each other in a conventional fashion, but with both blades being driven to reciprocate in mutual anti-phase.

It should be noted that the embodiments of the invention has been described above purely by way of example and that many other modifications and developments may be made thereto within the scope of the present invention.

Claims

1. A machine for performing a motional operation on an object, the machine comprising: a body, first and second operating elements for engaging the object and mounted for generally mutually-parallel reciprocating motion with respect to the body, and a drive mechanism for reciprocating the operating elements with respect to the body and out of phase with respect to each other.

2. A machine as claimed in claim 1, wherein the first operating element is one of a first group of such operating elements, and the drive mechanism is arranged to reciprocate the operating elements of the first group in phase with each other.

3. A machine as claimed in claim 2, wherein the second operating element is one of a second group of such operating elements, and drive mechanism is arranged to reciprocate the operating elements of the second group in phase with respect to each other.

4. A machine as claimed in any preceding claim, wherein the drive mechanism is arranged to reciprocate the first and second operating elements in anti-phase with respect to each other.

5. A machine as claimed in any of claims I to 3, and including a third operating element for engaging the object and mounted for reciprocating motion with respect to the body generally parallel to the first and second operating elements, the drive mechanism being arranged to reciprocate the first, second and third operating elements out of phase with respect to each other.

6. A machine as claimed in any preceding claim, wherein each operating element has an area for engaging the object, and the surface areas of the operating elements, or the aggregate surface areas of the operating elements in the groups thereof, are generally equal.

7. A machine as claimed in any preceding claim, wherein there is an odd number of the operating elements

8. A machine as claimed in any preceding claim, wherein each operating element is a brush.

9. A machine as claimed in any of claims 1 to 7, wherein each operating element provides a polishing or buffing surface.

10. A machine as claimed in any of claims I to 7, wherein each operating element has an abrasive surface.

11. A machine as claimed in any of claims 1 to 7, wherein the operating elements have complementary cutters.

12. A machine as claimed in any preceding claim, wherein the drive mechanism is arranged to reciprocate each operating element with simple harmonic motion.

13. A machine as claimed in any preceding claim, wherein the body is arranged to be held by hand.

14. A machine for performing a motional operation on an object, substantially as described 10 with reference to the drawings.