WO2007012311A1

WO2007012311A1 - Electric tool in particular battery-driven thread-cutting machine

Info

Publication number: WO2007012311A1
Application number: PCT/DE2006/001273
Authority: WO
Inventors: Peter Broghammer
Original assignee: Marquardt Gmbh
Priority date: 2005-07-27
Filing date: 2006-07-21
Publication date: 2007-02-01
Also published as: WO2007012311A8; EP1907172B1; EP1907172A1

Abstract

The invention relates to an electric tool, in particular a battery electric tool, such as a thread-cutting machine, drill, screwdriver machine or similar, comprising an electric motor (7) to drive a tool holder (5), for example for a thread cutter. The electric tool has a switch (8) with an operating member for switching on or off the power supply to the electric motor (7) and an inverter (10) for clockwise/anti-clockwise operation of the electric motor (7). The electric tool may optionally be provided with an electronic circuit (12) for speed control and/or regulation of the electric motor (7) and a short-circuit brake for the electric motor (7). The inverter (10) comprises a power semiconductor (13) for the non-contact inversion of the polarity of the power supply to the electric motor (7). The power semiconductor (13) is optionally controlled for the inversion by the electronic circuit (12) using an inversion signal, in particular, generated by an auxiliary contact (22).

Description

Power tool, in particular battery-powered tapping machine

The invention relates to a power tool according to the preamble of patent claim 1.

Such power tools are used as a thread cutting machine, drill, screwdriver o. The like., Which may be in particular a cordless power tool.

Cordless and / or mains operated power tools have an electric motor for driving a tool holder. Furthermore, the power tool is equipped with an actuator having a switch for switching on and / or off the power supply for the electric motor and a switch for the clockwise / counterclockwise rotation of the electric motor. As a switch, a conventional electrical switch is used. In advanced equipment, the power tool has electronics for speed control and / or regulation of the electric motor and short-circuit braking for the electric motor.

Such cordless screwdrivers are very often used for cutting threads. For this purpose, for example, a tap is used in the tool holder. Especially with larger workpieces that can not be edited with a stand or bench drill with adapted tapping, the use of such a cordless screwdriver offers.

However, the use of cordless screwdrivers for tapping has the disadvantage that the frequent switching between clockwise and counterclockwise rotation of the electric motor Lifetime of the switch for the clockwise / counterclockwise rotation due to wear of the electrical changeover contacts is achieved quickly. In chord mode, it may also happen that is already switched by the user when the electric motor is still rotating. This also leads to premature wear of the changeover contacts. Furthermore, the mechanical torque coupling is too inaccurate, which can lead to breakage of the tap by jamming or seizure. Conventional cordless screwdrivers are therefore only conditionally suitable for cutting threads. In particular, the life of the motor and the switching contacts of this cordless screwdriver is limited. The same disadvantages can also be observed with mains operated screwdrivers when they are used for thread cutting.

The invention has for its object to further develop the power tool in terms of its life. In particular, the battery and / or mains operated power tool should be suitable for threading.

This object is achieved in a generic power tool by the characterizing features of claim 1.

The switch of the power tool according to the invention is an electronic switch, which has in particular a power semiconductor for contactless switching the polarity of the power supply for the electric motor. The switching on and switching of the power supply for the electric motor thus happens electronically, so that no contact wear can occur as before, which in turn increases the life of the power tool. Further embodiments of the invention are the subject of the dependent claims.

In an advantageous embodiment of the power semiconductor can be controlled via an electronic circuit or electronics for switching, which can be done manually by the user and / or automatically in the presence of certain conditions. The electronics can thus advantageously operate the power tool programmatically in automatic operation. The switching can be triggered by means of a switching signal to the electronics. In manual operation, it is advisable that the switching signal is generated by an auxiliary contact leading only to a signal current, which in turn can be actuated by the user by means of an actuating element on the power tool.

The electronic circuit for switching can additionally serve as electronics for controlling the electric motor, so that there are no additional costs. Conveniently, the electronics have a microprocessor, which results in a very compact design control for the electric motor in the manner of a microprocessor control. Preferably, the electric motor is a brushless, electronically commutated (EC) electric motor that is particularly robust and durable. In addition, such EC electric motor is low maintenance, since an exchange of carbon brushes is eliminated. However, if desired, a brushed motor may also be used for the power tool. However, a power tool with a brushless direct current (DC) motor is particularly suitable for the special thread cutting functions, since even a large part of the electronic components of the existing controller can be used simultaneously for the electronics and / or the switch, so that a particularly cost-effective Solution is provided.

The system, consisting of EC motor and EC control electronics, can be easily provided both with conventional functions and with an extension to the additional functions for threading. Thus, the power tool on the one hand have a means for speed detection. On the other hand, the power tool may have a means for torque detection. Appropriately, the torque detection takes place by means of a current measurement. It is then possible to predetermine a maximum torque that can be set, for example, via an external switch, via a potentiometer or the like. Upon reaching the maximum torque then the electric motor is turned off. In a simple way, this adaptation to small or larger taps, different materials to be machined o. The like. Enables.

Such a power tool forms in a preferred embodiment, a completely new generation of devices for the niche market of threading. Basis of the invention is a cordless power tool that has a variety of electronic functions that make threading more effective and safer. Ideally, this is a power tool that also has the functions of a conventional cordless screwdriver, namely screwing, drilling, right / left switching, brake, speed control, shutdown o. The like. Has.

The power tool can be switched in a further embodiment between manual and / or automatic operation. Such a switching function offers the user the convenient way to automatically operate the power tool according to a predetermined program. If desired, however, the user can also intervene manually in the process.

The automatic operation with regard to thread cutting proceeds as follows. As soon as the actuator on the power tool is pressed by the user, the motor runs forward in the clockwise direction according to a leading characteristic, that is with a kind of ramp function, up to the ideal speed. This predefinable ideal speed varies, for example, according to the thread diameter and / or the material to be machined. Then the thread is cut by turning the tap in the clockwise direction with this ideal speed. Once the desired thread depth has been reached, or if the thread cutter is running in a blind hole, or if the user releases the actuating member, or if another condition is met, then the electric motor is automatically switched over to counterclockwise rotation. As a result, the tap is turned out of the thread again in reverse. It is advisable that the tap is moved at a higher speed in the counterclockwise than in the clockwise direction, so as to increase the performance of the power tool for tapping.

In addition, the number n of threads can be counted when screwing, which is possible for example in a simple manner by means of the electronics. When unscrewing the tap is then counted on at least the number of threads. For safety's sake, however, it can be counted a little further, for example to n + 3 threads. When this number is reached, the electronics switch the electric motor automatically. This process ensures a fast yet safe and high quality work cycle.

Extending is also an automatic chip breaking function by alternately forward and backward rotation according to the clockwise and counterclockwise rotation of the electric motor feasible. For this purpose, the electric motor rotates, for example, one revolution forward, and then a little more than one revolution back again. In tests, a reverse rotation of about 1.4 turns has proven to be particularly effective. Hereby the chip is surely broken. The acceleration and / or deceleration of the electric motor is expediently carried out with a suitable characteristic in the manner of a ramp function.

Manual operation is as follows. The user switches on and / or off the motor in this mode via the actuator. The speed is controlled by the user in the right direction over the actuation path of the actuator. Once the thread depth has been reached, the user switches to anti-clockwise rotation. If the preselected torque is exceeded, the machine switches off.

The advantages achieved by the invention are in particular that the switching on / off of the power tool and the switching between clockwise and counterclockwise for the power tool is made electronically. Therefore, no contact wear can occur, so that the life of the power tool is increased. In particular, as a further advantage when using an EC motor results in an additional increase in the life, since no brush wear occurs. Due to the very long service life of all components, the power tool can be used in multi-shift operation for a very long time as well as reliably and especially in the professional field.

In general, in such power tools electronic and / or electrical components for speed detection, current measurement, control by means of a microprocessor o. The like. Already exist anyway. These electronic and / or electrical components may be used at least in part for electronic switching and / or switching. Thus result at best slightly higher Cost of implementing the invention. At least a possibly higher price compared to conventional power tools is quickly compensated by the high life and high efficiency for the power tool.

If the power tool according to the invention is used as a threading tool, very short cycle times can be achieved in automatic mode. In addition, the service life of the taps is increased. This allows the introduction of new cordless power tools on the market for the threading specialty.

By eliminating a mechanical torque clutch due to the electronic torque detection, the power tool is shorter ausgestaltbar. Furthermore, the tap can also be used directly in the spindle, for example by means of a magnetic square drive, without using the drill chuck. This leads to a further shortening of the power tool, so that its handling is improved for the user.

An embodiment of the invention with various developments and refinements is shown in the drawings and will be described in more detail below. Show it

1 is a power tool for tapping,

Fig. 2 shows the power tool of FIG. 1 in plan view and

Fig. 3 is a block diagram for the control of the power tool.

In Fig. 1, a power tool 1 can be seen with a housing 2, which in a known manner as a drill, screwdriver o. The like. Can be used. In the present case, the power tool 1 is a cordless power tool which can be operated by means of a rechargeable battery 4 which can be inserted into the handle 3 on the housing 2. In a novel way that is Power tool 1 can be used as a thread cutting machine by a thread cutter 6 can be used in the tool holder 5 of the power tool 1.

As can be seen in Fig. 3, the power tool 1 has an electric motor 7 for driving the tool holder 5 via a transmission 14. For switching on and / or off the power supply for the electric motor 7, the power tool 1 has an on / off switch 8 with a user-operable, visible in Fig. 1 actuator 9. The electric motor 7 is by means of an electronic circuit 12, hereinafter also referred to as electronics 12, operated. The electronics 12, which includes a microprocessor and / or consists of a microprocessor, controls for the desired operation of the electric motor 7, an array of power semiconductors 13 for powering the electric motor 7 in the manner of a microprocessor control accordingly.

The switch 10 is designed as an electronic switch and has a power semiconductor for contactless switching the polarity of the power supply for the electric motor 7, wherein for this purpose the power semiconductor 13 for the Voltage supply of the electric motor 7 is used. For manual actuation of the electronic switch 10 by the user serves a visible in Fig. 1 actuator 11, which acts on a right / left switch 22.

Similarly, the power semiconductor 13 is also used for switching on the electric motor 7. The on / off switch 8 and the right / left switch 22 thus each comprise an auxiliary contact, which is connected to an input of the microprocessor 12. By operating the actuating member 9 and / or the actuating element 11, the auxiliary contact 8, 22 is switched, thereby generating an on / off switching signal and / or a switching signal, so that the electronic circuit 12, the power semiconductor 13 for switching on / off and / or switching over. Since the switching on / off and / or the switching of the load current to the electric motor 7 is carried out electronically, therefore, no contact wear can occur. At the auxiliary contacts 8, 22, however, only a small, no significant wear causing signal current occurs. The power tool 1 is further equipped with electronics for speed control and / or - regulation of the electric motor 7, this electronics in turn is formed by the microprocessor 12. For this purpose, the power tool 1 has a means for speed detection, wherein the detected at the electric motor 7 actual speed n is supplied to an input 15 of the microprocessor 12. The target speed is specified in a known manner by the path of movement of the actuator 9 designed as a pusher by the user. Furthermore, a short-circuit braking for the electric motor 7 is realized in the power tool 1.

The power tool 1 has a means for torque detection. The torque detection can be done by means of a current measurement on the electric motor 7. The measured current, which corresponds to the actual torque, is supplied to an input 16 on the microprocessor 12. The desired maximum torque can be specified by the user by means of an external switch, a potentiometer 17 or the like. On the housing 2 is to adjust the potentiometer 17 is a user-operable, visible in Fig. 2 knob 18. When the maximum torque is reached then the electric motor 7 is switched off by the microprocessor 12 via the power semiconductor 13. The knob 18 thus allows an adaptation to small or larger taps, different materials o. The like., To achieve an optimal result when tapping. It is preferred that the electric motor 7 is a brushless, electronically commutated (EC) electric motor which ensures a long-lasting, functionally reliable and low-maintenance power tool 1.

The power tool 1 has a switching function between manual and automatic operation, which are explained in more detail below. For this switching function, a switch 19 is arranged on the housing 2, as can be seen with reference to FIG. Another switch 20 is used to switch between drilling / Schraύb operation and tapping. Yet another switch 21 is used to switch on the also discussed below chipbreaking function. In automatic operation of the electric tool 1 for the thread cutting runs after actuation of the actuator 9 by the user of the electric motor 7 in the clockwise direction to the ideal speed. The predefinable ideal speed depends on various circumstances, such as the diameter of the thread to be cut. Appropriately, the run-up takes place with a kind of ramp function, that is, according to a predetermined characteristic, in order to avoid an overload. Then, the thread is cut by screwing the tap 6 in the clockwise direction of the electric motor 7. As soon as the desired thread depth is reached, it automatically switches over to the counterclockwise rotation of the electric motor 7. Of course, this also other conditions, for example, as soon as the tap 6 runs in a blind hole, as soon as the user releases the actuator 9 o. The like., Are used. Thereafter, the tap 6 is rotated out of the thread again in reverse. To save time, this can be done at a higher speed. In manual operation of the power tool 1, however, the user switches by means of the actuating element 11 manually between clockwise and counterclockwise rotation of the electric motor 7.

In addition, the subsequent process ensures a particularly fast and nevertheless safe working cycle. When screwing in the tap 6, the number n of threads is counted, to which the microprocessor of the electronics 12 can be advantageously used. When unscrewing the tap 6 is counted on at least the number of threads. However, it can also be counted, for example, n + 3 Gewindegärige, so that the tap 6 is certainly completely unscrewed. Upon reaching this number n or n + 3 in reverse, then the electronics 12 is automatically switched off together with the electric motor 7.

An automatic chip breaking function, which is particularly suitable for automatic operation, is realized in that the electric motor 7 is rotated alternately back and forth in accordance with its right and left rotation. For example, the electric motor 7 is rotated one revolution forward and then slightly more than one revolution backwards. The chip is then certainly broken. According to experiments carried out are particularly good results for the chipbreaker function achieved when the electric motor 7 is rotated in about 1.4 turns backwards. The acceleration and / or deceleration of the electric motor 7 can in turn be carried out with a suitable ramp function or according to another characteristic in order to prevent an overload of the tap 6. This makes it possible to produce threads of particularly good quality.

The invention is not limited to the described and illustrated exemplary embodiment. Rather, it also encompasses all expert developments within the scope of the invention defined by the claims. Although the invention is described with reference to a cordless power tool, it can also be used with power tools powered by mains voltage. Furthermore, a power tool according to the invention is advantageous not only for thread cutting, especially in the professional field, but also for other machining tasks.

Reference numeral list:

: Power tool: body: handle: battery: tool holder: tap: electric motor: on / off switch / auxiliary contact: actuator 0: (electronic) switch 1: actuator 2: microprocessor / electronic circuit / electronics 3: power semiconductor 4: gear 5: Input (to microprocessor for actual speed) 6: Input (to microprocessor for actual torque) 7: Potentiometer (for torque) 8: Rotary knob 9: Switch (for manual / automatic switching function) 0: Switch (for switching function drilling / tapping ) 1: Switch (for chip breaking function) 2: Right / left switch / auxiliary contact

Claims

P atentsports:

1. Power tool, in particular cordless power tool, such as

Tapping machine, drill, screw o. The like., With an electric motor (7) for driving a tool holder (5), for example for a tap (6), with an actuator (9) having switch (8) for on and / or Switching off the power supply for the electric motor (7), with a switch for the clockwise / anti-clockwise rotation of the electric motor (7), optionally with electronics (12) for speed control and / or regulation of the electric motor (7), and optionally with a short-circuit braking for the electric motor (7), characterized in that it is the switch to an electronic switch (10), in particular a power semiconductor (13) for contactless switching the polarity of the power supply for the electric motor (7).

2. Power tool according to claim 1, characterized in that the power semiconductor (13) is controlled manually and / or automatically via an electronic circuit (12) for switching, that preferably the switching is triggered by means of a switching signal, and further preferably that the switching signal Manual operation of a Hüfskontakt (22) is generated, which in particular by means of an actuating element (11) is actuated.

3. Power tool according to claim 1 or 2, characterized in that it is the electric motor (7) is a brushless, electronically commutated (EC) electric motor.

4. Power tool according to claim 1, 2 or 3, characterized in that the electronics (12) for switching in addition to the control of the electric motor (7), and that preferably the electronics (12) has a microprocessor, such that it is a microprocessor control is.

5. Power tool according to one of claims 1 to 4, characterized in that the power tool (1) has a means for speed detection.

6. Power tool according to one of claims 1 to 5, characterized in that the power tool (1) has a means for torque detection, which operates in particular by means of a current measurement, that preferably a maximum torque, for example via an external switch, via a potentiometer ( 17) o. The like. Can be specified, and that further preferably when the maximum torque of the electric motor (7) is switched off.

7. Power tool according to one of claims 1 to 6, characterized in that the power tool (1) can be switched between manual and / or automatic operation.

8. A method for preferably automatic operation of a power tool (1) for the thread cutting, in particular according to one of the preceding claims, characterized in that after actuation of the actuating member (9) of the electric motor (7) in the clockwise direction, in particular with a kind of ramp function on running up the ideal speed, then that the thread is cut by turning the tap (6) in the clockwise that once the thread depth is reached when the tap (6) runs in a blind hole as soon as the user releases the actuator (9) o. Like. The electric motor (7) is automatically switched to the counterclockwise rotation, and that thereafter the thread cutter (6), in particular at a higher speed, is rotated out of the thread again in the left-hand rotation.

9. The method according to claim 8, characterized in that upon insertion of the tap (6) the number n of threads, in particular by means of the electronics (12), is counted that preferably when unscrewing the tap (6) to at least the number of threads , For example, on n + 3 threads, is counted, and that further preferably upon reaching this number, the electronics (12), the electric motor (7) automatically switches off.

10. The method according to claim 8 or 9, characterized in that by alternately forward and backward rotation corresponding to the clockwise and counterclockwise rotation the electric motor (7) an automatic chip breaking function is realized, for example by the electric motor (7) rotates one revolution forward and then backward in about 1.4 revolutions, preferably the acceleration and / or deceleration of the electric motor (7) performed with a suitable ramp function becomes.