Improvements to router apparatus

Abstract

A router power tool having a housing and a base, the housing mounted to be moveable with respect to the base. The base and housing are connected by first and second extendable assemblies, at least one of the assemblies including biasing means to bias the housing away from the base. This extendable assembly has a control portion which can be moved, while located with the extendable assembly, from a first position in which the biasing means provides the biasing force and a second position in which the biasing means is released. In one embodiment, the router power tool includes safety stop portions to prevent movement of the tool holder while cutting tool changing is being performed. In another embodiment, a safety stop portion limits movement of at least one of the extendable assemblies when the cover is held by the power switch when in the on position.

Claims

1. A power tool which comprises: a housing and a base, said housing mounted to be moveable with respect to, and spaced from, the base, said housing including a motor to rotate a shaft, said shaft having a free end at which is located a tool holder for a cutting tool, said shaft extending from the housing such that the tool holder is located at or adjacent to the base and said housing is connected to the base by at least first and second extendable assemblies, at least one of the assemblies including biasing means located so as to provide a biasing force so as to bias the housing away from the base and the said at least one extendable assembly is provided with a control portion which is movable from a first position in which the biasing means is engaged to provide the biasing force and a second position in which the biasing means is released from providing the biasing force wherein said control portion includes a spring location portion which moves linearly out of the extendable assembly when the control portion is moved to the second position so that the control portion is retained with an elongate fixture member of the extendable assembly while in the second position.

2. A power tool according to claim 1 wherein said control portion is rotated between the said first and second positions and during which the control portion moves in a linear direction.

3. A power tool according to claim 1 wherein the control portion is locked in said first position by securing means.

4. A power tool according to claim 3 wherein the control portion movement is guided by a screw or a bayonet fitting between a male part formed in one of the control portion or an elongate member of the said assembly and a female part formed in the other of the said control portion or elongate member.

5. A power tool according to claim 1 wherein the biasing means is a coil spring and when the control portion is in the second position the spring extends along the extendable assembly to a substantially relaxed condition so as to remove or reduce the biasing force exerted.

6. A power tool according to claim 1 wherein the control portion is moved to a third position to allow removal of the biasing means.

7. A power tool according to claim 1 wherein the control portion is provided in the first position when the tool is to be located for use on a top side of a work surface and is moved to the second position when the tool is to be located for use on an underside of the work surface.

8. A power tool according to claim 1 wherein a biasing means is provided in both of the said extendable assemblies.

9. A power tool according to claim 8 wherein the control portion is provided for one of the said extendable assemblies to allow the adjustment of the baising force exerted by the biasing means located therewith and the said biasing force exerted thereby is greater than the biasing force of the biasing means located with the other said extendable assembly.

10. A power tool according to claim 1 wherein the tool includes a switch which allows the switching on and off of the motor and a cover is provided for the switch which is spring loaded to engage with the switch to retain the switch in the off position and the cover is held back by the switch, against the spring loading, when the switch is in the on position.

11. A power tool according to claim 10 wherein the cover further includes a safety stop portion which limits the movement of at least one of the extendable assemblies when the cover is held back by the switch in the on position.

12. A power tool according to claim 11 wherein the safety stop portion contacts with part of the top face of a guide arm of the extendable assembly to prevent further movement of the extendable assembly when the switch is in the on position whilst allowing access to the interior of the extendable assembly to allow a biasing means to be included in that extendable assembly.

13. A power tool according to claim 1 wherein a height adjustment mechanism is provided to allow adjustment of the position of the housing with respect to the base, said mechanism including a sprocket which engages teeth formed as a rack along a guide arm of an extendable assembly and the sprocket is selectively engaged by a coarse adjustment means or a fine adjustment means which are operated manually or by powered means.

14. A power tool according to claim 13 wherein the movement of the housing with respect to the base is a plunge movement in which a user exerts a movement force to move the housing towards the base with the adjustment mechanism disengaged.

15. A power tool according to claim 1 wherein the tool includes first and second handles, said handles located at, or adjacent to, the extendable members on opposing sides of the said shaft and wherein the handles are provided of different shapes.

16. A power tool according to claim 1 wherein the tool holder is moved through an opening in the base so that at least a portion of the tool holder lies to the side of the base plate opposing that at which the housing is provided so as to be accessible for the cutting tool to be located with and removed from the tool holder and the base includes engagement means for engagement with the tool holder when the power tool is switched off.

17. A power tool according to claim 1 wherein first and second handles are attached to the housing to allow a movement force to be exerted to move the housing towards the base and to grip the tool in use and wherein the first and second handles are asymmetrical.

18. A power tool according to claim 1 wherein the power tool includes a switch which allows the switching on and off of the motor and control of whether the cutting tool is capable of being rotated or not, a cover is provided for the switch such that that the motor cannot be accidentally activated once switched off and when the switch is moved to the on position the cover is held back by the switch, against a biasing force, said cover further includes a safety stop portion which limits the progress of at least one of the extendable assemblies when the cover is held by the switch in the on position and wherein the safety stop portion is formed to contact with the said guide arm of the said at least one extendable assembly to a sufficient extent to prevent further movement of the extendable assembly when the switch is in the on position and to allow a biasing means to be included in the said extendable assembly.

19. A power tool which comprises: a housing and a base, said housing mounted to be moveable with respect to and spaced from the base, said housing including a motor to rotate a shaft which includes a free end, a tool holder for a cutting tool located at said free end, said shaft extending from the housing such that the tool holder is located at or adjacent to the base and said housing is connected to the base by at least first and second extendable assemblies and a height adjustment mechanism is provided which includes a sprocket which engages teeth formed as a rack along a guide arm of at least one of the extendable assemblies and the movement of the housing with respect to the base is by a plunge movement in which the user exerts a movement force to move the housing towards the base, or is made via the height adjustment mechanism operated by hand or via powered drive connected thereto and wherein at least one extendable assembly is provided with a control portion which is movable from a first position in which the biasing means is engaged to provide the biasing force and a second position in which the biasing means is released from providing the biasing force and said control portion includes a spring location portion which moves linearly out of the extendable assembly when the control portion is moved to the second position so that the control portion is retained with an elongate fixture member of the extendable assembly while in the second position.

Description

(1) Specific embodiments of the invention are now described with reference to the accompanying drawings; wherein

(2) FIGS. 1a-c illustrate a perspective, elevation and plan views of first and second embodiments of a router tool in accordance with one embodiment of the invention;

(3) FIGS. 2a and b illustrate the router of FIGS. 1a-c with a spring release mechanism;

(4) FIGS. 3a-b illustrate the router of FIGS. 1a-c with dual springs;

(5) FIGS. 4a-b illustrate a switch safety interlock cover in accordance with one embodiment of the invention;

(6) FIGS. 5a-e illustrate views of a height adjustment mechanism for the housing with respect to the base; and

(7) FIG. 6 illustrates the selective attachment of a powered height adjustment means to the mechanism of FIGS. 5a-e.

(8) Referring firstly to FIGS. 1a-b there is illustrated a router power tool 2 in accordance with the invention in one configuration of use and, in FIG. 1c, the router power tool is shown in a second configuration of use. The router can be used in two main positions. The first position is that shown in the FIGS. 1a-c in which the same is located on and above a work surface on which a workpiece for which the tool is to be used is located. In an alternative position shown in FIG. 6 the router can be turned through 180 degrees so that the base 8 is attached to the underside of the work surface so that effectively the router is used upside down and is located below the work surface.

(9) In one configuration the base 8 may be attached to a guide plate 4 as shown in FIG. 1c, or may be attached directly to the work surface such as that provided as part of a workcentre of the type disclosed in the applicant's patent application GB2517640 and the contents of which are incorporated herein, or may be used in a freestanding mode as illustrated in FIGS. 1a-b.

(10) The router includes a housing 6 which is connected to the base 8 by first and second extendable members 10,12 so as to be movable in relation thereto as indicated by arrows 14,16. From the underside 18 of the housing extends a shaft 20, which at its free end includes a tool holder 22. The tool holder receives a tool 24 and the shaft, tool holder and tool are rotated about axis 26 by connection of the shaft with a motor (not shown) located within the housing 6.

(11) The tool passes through an aperture 28 in the base in order to engage and perform the work on the workpiece. The tool also includes first and second handles 30,32 which are located on the housing 6 on opposing sides of the same and typically at or adjacent to the first and second extendable assemblies 10,12 respectively. The handles are provided so as to allow the housing to be moved downwardly towards the base and generally to allow control of the tool in use.

(12) In accordance with one aspect of the invention, the handles are asymmetrical with one handle 28 elongate in form along axis 32 and the other handle 30, being substantially circular in shape with its centre positioned about axis 34. The provision of the different shaped handles allows the gripping and control of the tool to be at least maintained as much as with respect to conventional routers whilst, at the same time, allowing access to be more easily obtained to other features of the router located at or around the housing, such as the power on and off switch 36 and/or for access to be obtained in a more convenient and comfortable manner. By adopting this approach so the shape of each particular handle can be selected to suit its specific use.

(13) Referring now also to FIGS. 5a-e the position of the base 8 relative to the housing 6 is defined by the extendable assemblies 10, 12, with, in FIGS. 5a-e part of the extendable assembly 12 being shown. The extendable assembly includes a guide arm or post 66 which is fixed to the base 8 at it's lower end and is received within a fixture 68 on the housing 6. The adjustment of the housing 6 relative to the base plate 8 is performed in a plunge manner when the lever 99 is disengaged and the housing 6 can be forced towards the base against biasing means springs by the user exerting a force on the housing in the direction 16. When released the biasing means springs cause the housing to move in the direction 14 away from the base.

(14) When the lever 99 is engaged as shown then a height adjustment mechanism 70 is engaged to provide a more controlled relative movement of the housing 6 and base 8 and which, preferably allows user selection of either coarse and fine adjustment of movement.

(15) The height adjustment mechanism includes a sprocket 72 which engages teeth 74 on the guide arm 66. The sprocket 72 rotates on an axle 76 which is engagable with a coarse adjustment means which in this case is incorporated in the handle 30. The coarse adjustment means 30 is provided with a clutch mechanism which facilitates engagement between the sprocket 72 and the coarse adjustment knob 30 and the clutch mechanism includes a slidable sleeve 78 fitting over and rotationally fixed relative to a mounting shaft 80 and is engagable with the coarse adjustment means by axial movement along the mounting shaft 80. When the sleeve 78 engages with the coarse adjustment means of the handle 30, the relative position of the mounting shaft 80 and the coarse adjustment means is fixed until the sleeve is released, whereupon the sleeve returns to its original position under the action of a spring bias. As the mounting shaft 80 is directly connected to the sprocket 72, rotation of the handle 30 when the sleeve 78 is engaged, rotates the sprocket 72 causing the housing 6 to progress up or down the guide arm 66 teeth.

(16) A fine adjustment means 82 is also provided which engages with teeth formed on the surface of mounting shaft 80. The fine adjustment knob is mounted on a substantially vertical shaft 84 having a screw thread 86 which engages with the teeth 88 on the mounting shaft 80. Rotation of the fine adjustment knob 82 and hence vertical shaft 84 causes small rotational movements of the mounting shaft and hence the sprocket 72. These movements are smaller than those caused by rotation of the coarse adjustment means in the handle 30.

(17) FIG. 6 illustrates the tool 2 which is provided in a configuration in which the same is mounted on the underside of a work surface 100 as shown with the base 8 attached to the same. This illustrates how it can, especially in this mode, be difficult to access the coarse and fine adjustment means on the housing and extendable members from the top side 101 of the worksurface 100 which is where the user of the tool will be located. This problem is overcome in this aspect of the invention by attachment of a powered drive 102 to the adjustment knob 82 (not shown) so as to provide a drive connection which will achieve the rotation of the adjustment knob 82 when the drive means is powered. The powered drive is mechanically located via a clip portion 104 which locates on the housing 6 and is electrically connected via cable 106 to user controls 108 which include a selector 110 to allow fine or coarse adjustment to be achieved and a rotator 112 to allow the user to select the amount of adjustment to be achieved and therefore allows this to be done by the user remotely from the adjustment knob 82.

(18) The adjustment mechanism allows the housing 6 to be progressed towards the base 8. The working depth of the cutting tool in the tool holder 22 is defined by the extension of the cutting tool beyond the base 8 and the tool holder 22 can extend through the base 8 aperture 28 to maximise the cutting depth that can be achieved and this also allows greater access to the tool holder 22 for changing the cutting tool.

(19) Turning now to FIGS. 2a and b and 3a and b there is illustrated further detail relating to the extendable members 10, 12. The extendable members are typically telescopic in form, with an elongate member or guide arm 66 attached to the base and an elongate member fixture 68 attached or provided as part of the housing which overlap at their free ends and are slidingly located so as to allow adjustment of the distance between the housing and the base. The housing is biased towards the raised position by a biasing means spring 40 (shown in broken lines in FIG. 1a) which is a coil spring which extends along at least part of the length of the extendable assembly 12.

(20) As shown in FIGS. 2a and b, the extendable assembly 12 includes a control portion 42 which is movable between a first position shown in FIG. 2b and FIGS. 1a-c, and a second position shown in FIG. 2a. The control portion can be retained in the first position by the provision of securing means 44, shown in FIG. 1a which engage with a collar 46 on the control portion.

(21) When the control portion is in the first position, the spring end 48 is engaged and forced downwardly by a spring location portion 52 formed as part of the control portion 42 such that the spring biases the housing away from the base. This arrangement is as required when the router is used in the orientation shown in which the same is mounted on the top of a work surface and the tool is to be moved down or plunged towards the workpiece on the work surface. However, in another configuration of use, when the router is attached to the underside of the work surface as shown in FIG. 6, the housing is required to be moved upwardly and towards the underside of the work surface. This movement is typically caused by the user indirectly via a manual or powered winding mechanism which is attached to the router. In this configuration, and in order to allow the movement mechanism to be effective, it is desired to reduce the resistance to the movement of the housing towards the base and so in accordance with the invention the control portion 42 is moved to the second position by releasing the securing means 44, 46 and then rotating the control portion 42 knob 43 so as to cause a screw or bayonet style movement of the control portion 42 with respect to the housing 6 and in turn the the spring locating portion 52 moves linearly out of the extendable assembly 12 as indicated by arrow 54 in FIG. 2a. This, in turn, allows the spring 40 to extend and lengthen and so the biasing force of the same on the housing is reduced or removed when the control portion 42 is in the second position.

(22) FIGS. 3a and b illustrate a further embodiment of the extendable members which can be used in conjunction with, or separately from, the embodiment illustrated in FIGS. 2a and b.

(23) In this embodiment each of the extendable members 10, 12 are provided with a spring 56, 58 respectively. The provision of the spring in each of the extendable assemblies allows the downward force which is exerted by the user when gripping both handles to be substantially more uniformly spaced across the housing than is the case in the conventional apparatus with a spring in only one of the extendable assemblies. Also, the provision of the two springs means that the force required to be exerted by the springs can be split between the two springs meaning that each can be provided to have a reduced biasing force compared to the spring used when only one spring is provided. Furthermore, control portion 42 need only be provided for one of the said extendable assemblies, assembly 12, to allow the adjustment of the biasing force exerted by the biasing means spring 58 located therewith. Typically the biasing force which is exerted by that biasing means spring 58 is greater than the biasing force of the biasing means spring 60 located with the other extendable assembly 10 and therefore that spring condition need not be altered.

(24) Turning now to FIGS. 1a, 3a-b and 4a-b there is illustrated switch interlock cover 60 which is located in the housing to act with the motor switch 36 which is biased to an off position.

(25) The cover 60 is provided with a portion 62 which engages with the switch such that that the motor cannot be accidentally activated once switched off and typically the cover is spring loaded to engage with the switch to retain the switch in the off position. When a positive decision is made to move the switch to the on position the cover is moved by the switch, against the spring so as to move a safety stop portion 64 to partially overlie the extendable assembly 10 to limit the movement of the extendable assembly when the cover is held back in its retracted position by the switch in the on position.

(26) As the housing 6 moves closer to the base plate 8, the guide arm 66 moves within and will eventually extend above the sleeve 68 top face 94. Fixtures can be provided on the housing 6 to define the limit of travel of the guide arm 6 along the side of housing 6 and are positioned to correspond to the position of the guide arms when the housing 6 is at its lowest position relative to the base plate 8.

(27) The switch 36 receives the cover portion 62 in sliding engagement. The cover portion 62 covers and prevents access to switch 36 when the switch is in the off position and moves between that position and a position which allows access to the switch 36. The stop portion 64 of the cover extends between the cover portion 62 and housing 6. When the cover portion is not covering switch 36, stop portion 64 extends partially across the path of guide arm 66 as the housing is moved towards the base plate. When the stop portion 64 is in the position shown in FIG. 4b it is not possible for the guide arm 66 to travel to the full extent of travel and hence housing 6 is restricted from descending to its lowermost position relative to base 8 and so the tool holder 22 can be prevented from extending through the base 8 without the switch being moved to the off position. Once the switch 36 is switched off, cover 60 is spring loaded to return to the position to cover the switch 36 which removes the stop portion 64 from the path of the guide arm 66 allowing housing 6 to be moved closer to the base 8 and the power to the motor to rotate the tool holder is prevented from being activated.

(28) Importantly, the safety stop portion 64 is formed such that the same contacts with only a part of the extendable assembly 10 to a sufficient extent to prevent movement whilst, at the same time, allowing access to the interior of the extendable assembly 10. This therefore makes it possible to allow a biasing means to be included in the extendable assembly whereas, previously, the safety stop portion extend across the extendable assembly and thereby prevented the use of a biasing means in that assembly 10 which, in turn, meant that only one biasing means could be provided and that had to be provided in the other of the extendable assemblies 12 which led to the router tool potentially being unbalanced in use.

(29) There is therefore provided a router power tool with improved balance and ease of use with respect to the forces applied thereto by manual movement and also the force applied thereto by the biasing means located therewith.

(30) During the tool changing operation, the tool holder 22, while it extends through the aperture 28 in the base 8 can be immobilised by engagement of a releasable latch which includes an external plunger and a pin for engagement with a recess in the tool holder, all contained within the lower part of the housing 6. When the housing is at its lowest position it contacts with an inclined face inside the base 8 which pushes the pin to contact with the recess in the tool holder which extends beyond the base so that the tool holder is immobilised and in which position the tool held therein can be removed and replaced. To disengage the latching mechanism, the router is raised, removing the inclined face on the base from contact with the inclined face inside the base and the pin can then be retracted.