1. Field of the Invention
The present invention relates to an electromagnetically driven setting tool for driving in fastening elements and including a housing, a guide arranged, at least partially, in the housing, a magnetic anchor, displaceably arranged in the guide, and a magnetic coil arranged in the housing for displacing the magnetic anchor from an initial position of the magnetic anchor relative to the housing into an end position in which the magnetic anchor drives a fastening element in. The present invention also relates to a method of driving such a setting tool.
2. Description of the Prior Act
Setting tools of the type described above are used for driving fastening elements, in particular by a single drive-in movement of a piston in an object, e.g., a constructional component.
In the electromagnetically driven tools, the piston is formed as a magnetically conducting anchor that is accelerated by a magnetic coil. The impact or drive-in energy amounts to about 7 J, dependent on a limitation of the acceleration path and the coil size.
A setting tool of the type disclosed above is described in a German Publication DE 3937794 A1. The setting tool has a coil arranged in a tool housing and a magnetic anchor driven by the coil. The coil is supported, at its end facing in a direction opposite the drive-in direction, against the housing by a spring that acts as a rebound damper. A tension spring, which is arranged between the supporting end of the housing and the magnetic anchor, is used for returning the magnetic anchor in its initial position after completion of a setting or drive-in process.
A drawback of the known setting tool consists in that it has a small impact or drive-in energy that is not always sufficient for driving a fastening element, e.g., a nail in a hardened construction component.
Accordingly, an object of the present invention is a setting tool of the type described above and a method of driving the same in which the foregoing drawback of the known tool is eliminated, and a high drive-in energy is provided in a technically simply way.
This and other objects of the present invention, which will become apparent herein after, are achieved by providing a force accumulator which becomes loaded by the magnetic anchor when the magnetic anchor is displaced, in a first phase of a setting process, by the magnetic coil in a direction of the force accumulator to an intermediate position of the magnetic anchor relative to the housing, and which accelerates the magnetic anchor, in a second phase of the setting process, in an opposite direction when the magnetic anchor is displaced by the magnetic coil from the intermediate position to the end position.
With such force accumulator, which becomes loaded upon purposeful acceleration of the magnetic anchor or piston in the direction toward the force accumulator, the magnetic anchor is driven, during a single drive-in impact, upon changing the polarity of the magnetic coil, by both the magnetic coil and the force accumulator in the drive-in direction. There is provided, thus, in sum a noticeably higher drive-in energy per impact than in conventional electromagnetically driven setting tools.
Advantageously, there is provided, in the setting tool, a control device which applies, in the first phase of the setting process, a first polarity to the magnetic coil for accelerating the magnetic anchor in the direction of the force accumulator, and which applies, in the second phase of the setting process, a second polarity to the magnetic coil for accelerating the magnetic anchor in the opposite direction.
The control device which, e.g., is formed as an electrical circuit and which, e.g., can include a microprocessor can provide a precise control of the magnetic coil within few milliseconds, which makes a rapid succession of separate drive-in processes possible.
Advantageously, the force accumulator is formed as a compression spring having one of its ends fixedly secured to the housing with its opposite end adjacent to the magnetic anchor remaining free. With this arrangement, with which the spring can be brought in a direct contact with the magnetic anchor with its free end, energy looses, which can result from a further mechanical contact or fiction, are prevented.
Advantageously, the magnetic anchor is located, in its initial position, in a region of the guide which is substantially surrounded by the magnetic coil. Thereby, on one hand, a sufficient displacement path is provided between an end of the magnetic anchor adjacent to the force accumulator and the force accumulator. Thereby, a sufficient acceleration path is provided for the magnetic anchor. On the other hand, the opening of the magazine with fastening elements toward the guide remains unobstructed, which insures feeding of fastening elements into the guide. In order for the magnetic coil to apply a maximum force to the magnetic anchor before the magnetic anchor moves in the direction of the force accumulator, a mechanical holding element such as, e.g., a pawl can be provided and which would release the magnetic anchor only then when the field strength of the magnetic coil reaches its maximum.
However, the magnetic anchor can also be located, essentially, in a region of the guide remote from the force accumulator.
Advantageously, the magnetically anchor is formed as a piston so that it can act directly on a fastening element, without any energy-consuming intermediate elements arranged between the anchor and the fastening element.
Advantageously, there is provided restoring means for returning the anchor from its end position to its initial position. This permits to define the initial position using very simple means, e.g., the restoring means can be formed as a tension spring.
According to the inventive method, in a first phase of energization of the magnetic coil, i.e., in the first phase of the setting process, the magnetic anchor is displaced against the force accumulator, whereby the force accumulator is loaded. In the second phase of the energization of the magnetic coil, i.e., in the second phase of the setting process, when the polarity of magnetic field of the coil is reversed, the magnetic anchor is accelerated, as a result of unloading of the force accumulator, in the opposite direction, i.e., in the setting or drive-in direction.
With the inventive method, at which the magnetic anchor or piston, in a first phase, is accelerated in a direction opposite the drive-in or operational direction against the force accumulator, and is accelerated in the drive-in direction only in the second phase, a noticeably high impact or drive-in energy of the setting tool is achieved.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiment, when read with reference to the accompanying drawings.
The drawings show:
A setting tool 10 according to the present invention, which is shown in
The setting tool is further provided with a handle 27 on which an activation switch 26 for initiation of a setting process with the setting tool 10 is arranged. In the handle 27, there is further arranged a current source, which is generally designated with a reference numeral 22, for supplying the setting tool 10 with electrical energy. The current source 22 includes one or more accumulators 23 which is (are) located in the accumulator receptacle 24. Electrical conductors 25 connect the accumulator(s) 23 with a control device 20 that is connected, in turn, with the magnetic coil 12 and, if necessary, with other consumers of the electrical power by electrical conductors 21. It should be understood that, alternatively, the electrical energy can be supplied from a network. In the initial position 30, which is shown in
When the setting tool 10 is pressed against a constructional component U, as shown in
In
As a result of the reversed polarity of the magnetic field in the magnetic coil 12, an acceleration force in the direction of arrow 35 would act on the magnetic anchor 14 (see
Though the present invention was shown and described with references to the preferred embodiment, such is merely illustrative of the present invention and is not to be construed as a limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. It is, therefore, not intended that the present invention be limited to disclosed embodiment or details thereof, and the present invention includes all variations and/or alternative embodiments within the spirit and scope of the present invention as defined by the appended claims.
Number | Date | Country | Kind |
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10 2004 010 319.4 | Mar 2004 | DE | national |