WO2007093959A1

WO2007093959A1 - Power tool

Info

Publication number: WO2007093959A1
Application number: PCT/IB2007/050469
Authority: WO
Inventors: Steen Mandsfelt Eriksen
Original assignee: Advance Design Ltd.
Priority date: 2006-02-14
Filing date: 2007-02-13
Publication date: 2007-08-23

Abstract

A power tool including a casing (2) with a front part (3) and a rear part (4); a driving motor (6) fitted in the casing (2), which when connected to a power source (26) rotates a driving spindle facing the front part of the casing, and defining an axis (31) ; a turret head (10) , which is fitted to the front part (3) of the casing (2) rotatable about an axis (29), which forms an angle with the axis (31) of the driving spindle (7); a number of tool holders (11,12), which with a mutual angular distance is fitted on the turret head (10) each rotatable about its own axis (30), and is designed to be tightened each by its own tool (13,14); one on each tool holder (11,12) coaxially fastened driven spindle (15) , which defines an axis (30); and coupling means (9,17) to couple the driven spindles (15) of the tool holders (11,12) rotatably together with the driving spindle (7) when the tools holders (11,12) at rotation of the turret head (10) one by one has been made to occupy a predetermined operative position in relation to the casing (2). The coupling means include a driven gear wheel (17), which is coaxially fitted to each of the driven spindles (15) , and a driving pinion (17) , which is coaxially fitted to the driving spindle (7). The power tool (1,28) according to the invention is easy, fast and safe to operate and it is ergonomically designed.

Description

Power tool

The invention relates to a power tool which comprises a casing with a front part and a rear part; a driving motor placed in the casing, which when connected to a power source rotates a driving spindle facing the front part of the casing and defining an axis; a turret head, which is fitted to the front part of the casing rotatable about an axis, which forms an angle with the axis of the driving spindle; a number of tool holders, which with a mutual angular distance is fitted on the turret head each rotatable about its own axis, and arranged to be tightened each by its own tool; one on each tool holder coaxially fastened driven spindle, which defines an axis; and coupling means to couple the driven spindles of the tool holders rotatably together with the driving spindle when the tools holders at rotation of the turret head one by one have been made to occupy a predetermined operative position in relation to the casing.

Tools of this type are by way of example known from the patent document GB 633,408, which mentions a hand-held tool with chucks for tightening tools to perform certain operations. The chucks have been rotatably fitted to a turret head, which at rotation one by one can put a chuck in operative position. In the operative position the driven spindle of the chuck is coupled together with den driving spindle by means of a spring-loaded claw clutch. A spring-loaded ratchet that can be displaced in a way in the casing meshes during this with a recess for each chuck in the turret head, and thus maintains this in position. A manually operated triggering mechanism serves as a trigger of the claw clutch so the turret head is allowed manually to be rotated in order to bring the next tool in an operative position.

A frequently occurring work consists of predrilling a hole by means of a drill and then fastening a screw in the hole by means of a screw bit. However, when a conventional tool with only one chuck is used for this purpose the work is complicated and time-consuming as it requires the following operations .

The drill is fastened in the chuck while the tool is inoperative. The hole is predrilled by activating the tool. The tool is deactivated. The chuck is opened. The drill is removed. The screw bit is fastened in the chuck, and the screw is finally fastened in the predrilled hole by reactivating the tool.

Alternatively, two power drills can be used with each their own tools, but in this case, performing the work will also be complicated and time-consuming as the operator has to put down one power drill each time he has to use the other.

When the above mentioned work has to be performed a number of times, the above mentioned known tool can advantageously be used as the drill and the screw bits can then be fastened in their own chuck which is then in turns brought in the operative position by rotating the turret head.

However, the known tool has a valuable and complicated construction, which is also difficult and strenuous to work with as both the manually operated triggering mechanism as well as the manually operated turret head are constructed such that it is contrary to basic ergonomic principles. Furthermore, there is a risk that the operator is hurt when he with one hand holds the tool and with the free hand has to operate both the triggering mechanism and the turret head as the free hand during this necessarily must be close to the frequently sharp tools that are at the same time moving. Further, it is not immediately easy to find exactly those positions where a driven spindle will be coupled with the driving spindle, as it is necessary first to have the spring- loaded ratchet mesh with the proper recess, which cannot be seen during this.

The disadvantages of the abovementioned known power tool are according to the invention remedied by,

in a first aspect of the invention providing a power tool of the type as stated in the opening paragraph which is easier to operate than previously known,

in a second aspect of the invention providing a power tool of the type as stated in the opening paragraph which is faster to operate than previously known,

in a third aspect of the invention providing a power tool of the type as stated in the opening paragraph which when operated provides the operator with more safety from being hurt by the tools than previously known,

in a fourth aspect of the invention providing a power tool of the type as stated in the opening paragraph which is ergonomically designed,

in a fifth aspect of the invention providing a power tool of the type as stated in the opening paragraph which is designed to safely and efficiently rotate the turret head to positions where the tool holders one by one are in the operative position,

in a sixth aspect of the invention providing a power tool of the type as stated in the opening paragraph which is of a simple construction.

The novelty and distinctive according to the invention, whereby this is accomplished, is that the coupling means comprise a driven gear wheel which is coaxially fitted to each of the driven spindles and a driving pinion which is coaxially fitted to the driving spindle.

By use of this arrangement of the power tool a separate coupling is saved as well as a mechanism for manually triggering the coupling whereby the tool attains a simple construction and at the same time is fast and easy to operate. This is particularly due to the driven spindle being automatically coupled with the driving spindle by merely rotating the turret head so that the two gear wheels are in meshing with each other and that the driven spindle and the driving spindle are automatically unmeshed by rotating the turret head again, so the two gear wheels are unmeshed. Thus, the tool holders are one by one brought to the operative position in the tool simply by rotating the turret head.

According to the invention both the driving pinion and the driven gear wheels can be conical, and the half apex angle of the driving pinion may equal the angle which its axis forms with the axis of the turret head, while the half apex angle of the driven gear may equal the angle which the axis of these gear wheels forms with the turret head, when the associated tool holder is in the operative position.

Thus, it is advantageously achieved that the driven gear wheels can easily mesh and unmesh with the driving pinion when the turret head rotates the tool holders in and out respectively of the operative position, during which the driven gear wheels describe a section of a circular track with the same axis as the turret head.

In an advantageous embodiment the driving pinion can according to the invention be distanced further from the axis of the turret head, viewed in a direction transverse to this axis, than a driven gear wheel in the operative position, whereby the driving pinion may taper in the direction of the rear part of the casing, while the driven gear wheel may taper in the direction of the front part of the casing.

Thus, the turret head has an especially compact construction. Another advantage is that the moment, which during an operation is produced partly by the pressure of the operator to the power tool partly by the reaction force of the operative tool, is reduced.

Consequently the operator will be able to perform the operations with an equally reduced deployment of force. Thus, the power tool is convenient and pleasant to operate.

Alternatively, the driving pinion can be distanced less from the axis of the turret head, viewed in a direction transverse to this axis, than a driven gear wheel in the operative position and the driving pinion may taper in the direction of the front part of the casing, while the driven gear wheel may taper in the direction of the rear part of the casing, whereby the gear wheels achieve an advantageous design.

In an especially advantageous embodiment according to the invention the axis of the driving pinion can be parallel to the axis in a driven gear wheel in the operative position. This arrangement involves that the power tool achieves expedient construction and that the driving pinion and the driven gear wheels advantageously achieve the same conicity.

Furthermore, the power tool can according to the invention include a driven gear rim, which is designed on the turret head with the same axis as this and a positioning motor, which is fastened in the casing and fitted with an output shaft with a positioning gear wheel that meshes with the gear rim. Instead of as conventionally having to rotate the turret head manually the operator now rotates the turret head simply by activating the positioning motor.

In addition, the contact for activating the positioning motor can advantageously be fitted in a suitable distance from the tools whereby the operator is able to use the power tool without any risk of being hurt by swinging tools. Thus, the power tool according to the invention is safe to operate.

Moreover, the power tool achieves an advantageous ergonomic design when the contact of the positioning motor and the contact of the driving motor are placed such that they both can be reached with the fingers on the same hand such that the operator with ease will be able to operate the power tool.

According to the invention the power tool may also include a circuit, which is supplied with current from a power source and is designed such that the driving motor and positioning motor cannot simultaneously be connected to the power source. Thus, the risk is eliminated that the turret head rotates while a tool operates.

Furthermore, the circuit can according to the invention include sensors on the turret head and the casing respectively for concurrently determining the positions of the turret head where a tool holder is in the operative position. The sensors in the circuit ensure that the turret head stops safely and effecttively when it during rotation has reached an operative position and this position is maintained for as long as desired.

In an advantageous embodiment according to the invention the circuit can further be designed in such a way that the acceleration at the beginning and ending of the turret head of position is comparatively small . Thereby, it is advantageously achieved that the torque generated during this by the inertia of the turret head and the tool holder and which the operator is to absorb is kept on a small level. Furthermore, the driven gear wheels are calmly and safely meshed and unmeshed with the driving pinion.

In order to avoid that the tools of the power tool unintentionally cause damage to the equipment and/or persons when the turret head is rotated the circuit according to the invention can be fitted to interrupt the power supply to the positioning motor due to a pre-determined maximum current. In doing so the rotation of the turret head is stopped when this strength of current has been reached, whereby possible damage is avoided or at least reduced to an insignificant level.

The positioning motor can according to the invention in an especially advantageous embodiment be a stepper motor, which is fitted to through the positioning gear wheel and gear rim stepwise rotate the turret head so that a new tool holder with tools is each time put in the operative position which is then maintained by the now stopped stepper motor. Thereby the need is eliminated for separate stops in order to maintain the tool holders one at a time in the operative position.

Furthermore, the stepper motor can be fitted with a self- sustaining gear, e.g. a worm gear drive for effectively maintaining the turret head in position when the current to the stepper motor is disconnected and the motor therefore has stopped.

The invention is explained further below, as only exemplary embodiments are described and further advantages and technical characteristics are indicated according to the invention referring to the figure, where Fig. 1 is a perspective view, partly in section, a first embodiment of a power tool according to the invention,

Fig. 2 is a diagrammatic view of a circuit to the power tool shown in fig. 1,

Fig. 3 shows on a larger scale a side view, partly in section, of a fragment of a second embodiment of a power tool according to the invention,

Fig. 4a, b show on an even larger scale two driven gear wheels and a driving pinion to the embodiments shown in figs. 1 and 3 of the power tool according to the invention partly in an operative position, partly in a change position.

In the following it is assumed that the tool holders, which belong to the power tool according to the invention, are of the type that are commonly used in a power drill and that are called collet chucks.

Fig. 1 shows a first embodiment 1 of the power tool, which is hand-held and includes a casing 2 with a front part 3 and a rear part 4 that are designed with a handle 5 for holding the power tool typically with one hand. A part of the power tool casing has been removed in order better to see its design in detail .

A driving motor 6 has been fitted in the casing with a driving spindle 7 that have been journaled in a bearing 8 and fitted with a gear wheel 9.

On the front part of the casing there is a rotatably fitted turret head 10 and thereon two collet chucks 11 and 12 have been fitted rotatably with a mutual angular distance of 180° for the fastening of tools 13 and 14 respectively. In the shown case the tool 13 in the chuck 11 is a drill and the tool 14 in the chuck 12 is a screw bit.

It is noted that within the scope of the invention more than two chucks may be fitted to the turret head and other tools than the ones shown in the chucks may be fastened.

The chucks 11 and 12 are both connected with a driven spindle 15, which is journaled in bearings 16 and fitted with driven gear wheels 17.

The top chuck 11 - seen in the figure - is in an operative position where its driven gear wheel 17 meshes with the driving pinion 9. By rotating the turret head 180° the chucks 11 and 12 change place so that it is now chuck 11 which is in the operative position where its driven gear wheel 17 meshes with the driving pinion 9.

In the shown case the turret head is rotated by a driven gear rim 18, which is fitted on the turret head with the same axis as this and a positioning gear wheel 19, which meshes with the gear rim 18 and is fitted on the output shaft 21 of a stepper motor 20. This arrangement allows the operator to put the chuck in the operative position simply by activating the stepper motor.

When activating the stepper motor the turret head is rotated accurately and efficiently to the positions where the chucks alternately are in the operative position and these positions are then maintained by stopping the stepper motor.

When using the abovementioned arrangement with a gear rim on the turret head and a positioning gear wheel on the stepper motor it is achieved that the operator both can change the position of the tools and maintain this position without during this as conventionally having to rotate the turret head and manipulate some stops manually. Thus, the power tool according to the invention is fast, safe and convenient to operate.

The power tool is supplied with current from a power source, which can be the power line (not shown) and/or a battery (not shown) . The power source is by not shown power cords connected to the driving motor 6 through a first contact 23 and with the stepper motor through another contact 24.

Both contacts are placed in such a great distance from the tools 13 and 14 that the operator will be capable of operating the tool without any risk of being hurt by a rotating tool or by tools that swing when the turret head is rotated.

Furthermore, the contacts 23 and 24 are placed so close to each other that the operator with ease can reach both contacts with his fingers on one hand. Thus, the power tool is ergonomically designed and therefore convenient and pleasant to operate.

The power tool according to the invention can advantageously be used when a certain work is to be performed which includes two or more different operations and especially when the work has to be repeated.

By way of example can be mentioned work, which consists of screwing a screw (not shown) into an object (not shown) . This work is performed fast and easy with the power tool as shown in fig. 1 by firstly pre-drilling a hole in the object with the drill 13 in the chuck 11, rotating the turret hear with the stepper motor 20 and then screwing the screw into the pre- drilled hole with the screw bit 14.

Fig. 2 is a diagrammatic view of a circuit 25 to the power tool shown in fig. 1. The circuit is supplied with current from a power supply 26. The driving motor 6 and the stepper motor 20 are inserted in the circuit in a parallel connection where both motors are connected with the same contact 27.

As can be seen, the contact 27 is designed as a toggle switch, which does not allow the operator to simultaneously activate both the driving motor 6 and the stepper motor 20. In the shown case the driving motor 6 is activated while the stepper motor 20 is deactivated. In the second position of the toggle switch the stepper motor 20 is activated while the driving motor 6 is deactivated. Thus, the risk is eliminated that the operator inadvertently rotates the turret head while the operator simultaneously works on an object with a rotating tool .

As mentioned, in fig. 2 a toggle switch is used for alternately activating the driving motor and the stepper motor. By way of example instead a sliding switch or other contact arrangements are used that ensure that the driving motor and stepper motor cannot be activated simultaneously.

Fig. 3 in fragments shows a second embodiment 28 of a power tool according to the invention. In this case too a part of the power tool casing is removed in order better to see its design in detail.

This second embodiment 28 of the power tool according to the invention corresponds essentially to the first embodiment 1 of the tool according to the invention shown in fig. 1 and described above. Thus, the same reference numbers have been used for the same parts .

However, in the second embodiment the power tool 28 has no gear rim, positioning gear wheel and stepper motor for rotating the turret head, which therefore in this case must be rotated manually and in addition must be kept in position by manually operated stops (not shown) , which function between the turret head and the casing.

When tools have to be changed during work, the turret head 10 is rotated about its axis 29 so that a new chuck will be in the operative position. In fig. 3 it is the chuck 11, which is in the operative position where the driven gear wheel with the axis 30 meshes with the driving pinion 9 with the axis 31.

Both the driven gear wheels 17 as well as the driving pinion 9 are conical. In fig. 3 the driven gear wheel 17 is, seen in the figure, under the driving pinion 9 in the operative position. In this case the driven gear wheel tapers in the direction of the front part of the casing 2, while the driving pinion tapers in the direction of the rear part of the casing.

In the operative position the axis 30 of the driven gear wheel is parallel to the axis 31 of the driving pinion and the two axes 30 and 31 intersect the axis 29 of the turret head under an angel α corresponding to the half apex angle of the conical gear wheels. Thus it is achieved that the operative driven gear wheel 17 meshes with the driving pinion 9 along an area of meshing, which is parallel to the axis 29 of the turret head. Thus, the teeth of the driven gear wheel can mesh and unmesh correctly with the teeth of the driving pinion when the turret head is rotated.

However, if the half apex angle of the conical gear wheels deviates from the angle, which their axes form with the axis of the turret head, the teeth rotate obliquely in the area of meshing with respect to each other resulting in the teeth being subjected to uneven wear and thereby the service life of the gear wheels is reduced. Larger deviations would have the effect that the driven gear wheel will not be able to mesh with the driving pinion. As mentioned above, the driven gear wheel is in fig. 3 under the driving pinion in the operative position, and the driven gear wheel tapers in the direction of the front part of the casing while the driving pinion tapers in the direction of the rear part of the casing.

In an alternative embodiment (not shown) the driven gear wheel is above the driven gear wheel and tapers in the direction of the rear part of the casing in the operative position, while the driving pinion tapers in the direction of the front part of the casing.

Fig. 4a shows, seen in the direction of the axis 29 of the turret head 10, the gear wheels 9 and 17 of the power tool, in the positions shown in figs. 1 and 3. As can be seen the operatively driven gear wheel 17 is under the driving pinion 9, while the other gear wheel 17, which in fig. 4a is not operative, is under the operative gear wheel. The axis of the turret head is seen as a point and the same applies to the area of engagement between the operatively driven gear wheel 17 and the driving pinion 9, as the half apex angle of the conical gear wheels, as mentioned above, are equal to the angle, which their axes 30 form with the axis 29 of the turret head.

Fig. 4b shows the same but with the turret head 10 rotated an angle of 30° in the direction of the arrow, whereby the former operatively driven gear wheel 17 is rotated out of its mesh by the driving pinion 9. During the rotation of the turret head the driven gear wheels 17 move along a circular track and by a rotation of 180° the two driven gear wheels have changed position, as it is now the other driven gear wheel 17, which is in operative position.

Furthermore, the power tool according to the invention obtains an advantageously configuration when the apex angle of the driven gear wheel is between 80° and 120°, preferably between 90° and 110° and especially between 95° and 105°.

Claims

1. A power tool including, a casing (2) with a front part (3) and a rear part

(4), a driving motor (6) fitted in the casing, which when connected to a power source (26) rotates a driving spindle (7) facing the front part (3) of the casing, which defines an axis (31) ,

- a turret head (10), which is fitted to the front part (3) of the casing (2) rotatable about an axis

(29) which forms an angle with the axis (31) of the driving spindle (7), a number of tool holders (11, 12), each fitted to the turret head (10) with a mutual angular distance and rotatable about an axis (30) and being fitted for fastening of each tool (13, 14),

- a driven spindle (15) coaxially fastened to each tool holder (11, 12), defining an axis (30), and coupling means (9, 17) for coupling the driven spindles (15) of the tool holders (11, 12) rotatably with the driving spindle (7) when the tool holders

(11, 12) during rotation of the turret head (19) one at a time are brought to occupy a pre-determined operative position with respect to the casing (2) , characterized in that the coupling means (9, 17) include a driven gear wheel (17) which is coaxially fitted to each of the driven spindles (15) , and a driving pinion (9) , which is coaxially fitted on the driving spindle.

2. A power tool according to claim 1 characterized in that both the driving pinion (9) as well as the driven gear wheels (17) are conical, whereby the half apex angle of the driving pinion (9) equals the angle CX, which this axis (31) forms with the axis (29) of the turret head (10) and. the half apex angle of the driven gear wheels

(17) equal the angle α, which their axis (30) form with the axis (29) of the turret head (10) when the corresponding tool holders (11, 12) are in the operative position.

3. A power tool according to claim 1 or 2 characterized in that the driving pinion (17) is at a larger distance from the axis (29) of the turret head (10), seen in a direction transverse to this axis, than a driven gear wheel (17) in the operative position and the driving pinion (9) tapers in the direction of the rear part (4) of the casing (2), while the driven gear wheel (17) tapers in the direction of the front part (3) of the casing.

4. A power tool according to claim 1 or 2 characterized in that the driving pinion (17) is at a smaller distance from the axis of the turret head (10) , seen in a direction transverse to this axis, than a driven gear wheel (17) in the operative position and that the driving pinion (9) tapers in the direction of the front part (3) of the casing (2) while the driven gear wheel (17) tapers in the direction of the rear part (4) of the casing (2) .

5. A power tool according to any of the claims 1 - 4 characterized in that the axis of the driving pinion (9) is parallel to the axis (30) in a driven gear wheel (17) in the operative position.

6. A power tool according to any of the claims 2 - 5 characterized in that the apex angle of the driven gear wheel (17) is between 80° and 120", preferably between 90° and 110° and most preferably between 95° and 105°.

7. A power tool according to any of the claims 2 - 5 characterized in that it includes a driven gear rim (18), which is designed on the turret head (10) with the same axis (29) as this and a positioning motor (20), which is fitted in the casing (2) and which is fitted with an output shaft (21) with a positioning gear wheel (19) which meshes with the gear rim (18) .

8. A power tool according to claim 7 characterized in that the power tool (1, 28) includes a circuit (25) , which is supplied with current from a power source (26) and is designed such that the driving motor (6) and positioning motor (20) cannot simultaneously be connected to the power source (26) .

9. A power tool according to claim 8 characterized in that the circuit (25) is designed to interrupt the power supply to the positioning motor (20) due to a predetermined maximum current.

10. A power tool according to claim 7, 8 or 9 characterized in that the positioning motor (20) is a stepper motor (20) .