SETTING TOOL

Description

[0001] The present invention relates to a setting tool for driving fastening elements into a substrate.

[0002] Such setting tools typically have a fastener receptacle, from which a fastener is inserted into the substrate along a setting axis. A driving element is driven by a drive along the setting axis toward the fastener.

[0003] US Pat. No. 6,830,173 B2 discloses a setting tool with a drive for a driving element. The drive comprises an electrical capacitor and a coil. To drive the driving element, the capacitor is discharged via the coil, exerting a Lorentz force on the driving element, causing it to move toward a nail.

[0004] DE 23 30 958 A1 discloses the preamble of independent claim 1.

[0005] Another example of a setting tool is also known from US 2003 / 183670 A1.

[0006] The object of the present invention is to provide a setting tool of the aforementioned type in which a high degree of efficiency and / or a good setting quality is guaranteed.

[0007] The object is achieved in a setting tool for driving fastening elements into a substrate, comprising a receptacle which is provided for receiving a fastening element, a driving element which is provided for conveying a fastening element received in the receptacle along a setting axis into the substrate, a drive which is provided for driving the driving element along the setting axis towards the fastening element, wherein the drive comprises an electrical capacitor, a squirrel-cage rotor arranged on the driving element and an excitation coil through which current flows during a rapid discharge of the capacitor and generates a magnetic field which accelerates the driving element towards the fastening element, and wherein the setting tool comprises a control unit which is suitable forto control the energy level of the current flowing through the excitation coil during rapid discharge of the capacitor. Preferably, the control unit is capable of continuously adjusting the energy level of the current flowing through the excitation coil during rapid discharge of the capacitor.

[0008] A capacitor, within the meaning of the invention, is an electrical component that stores electrical charge and the associated energy in an electric field. In particular, a capacitor has two electrically conductive electrodes between which the electric field develops when the electrodes are electrically charged to different degrees. A fastening element, within the meaning of the invention, is understood to be, for example, a nail, a pin, a clamp, a clip, a bolt, in particular a threaded bolt, or the like.

[0009] An advantageous embodiment is characterized in that the capacitor is charged with a charging voltage at the beginning of the rapid discharge, wherein the control unit is adapted to control the charging voltage. Preferably, the capacitor is charged in a charging process prior to the rapid discharge, wherein the charging process is controlled by the control unit.

[0010] An advantageous embodiment is characterized in that the control unit is suitable for controlling the amount of energy of the current flowing through the excitation coil during the rapid discharge of the capacitor as a function of one or more control variables.

[0011] A particularly advantageous embodiment is characterized in that the setting tool has a means for detecting a temperature of an environment and / or the setting tool, wherein the one or more control variables comprise the detected temperature. Preferably, the detected temperature is a temperature of the excitation coil. Likewise, the charging voltage of the capacitor during rapid discharge of the capacitor is set higher the higher the detected temperature. This makes it possible to compensate for an ohmic resistance of the excitation coil that increases with increasing temperature.

[0012] Another particularly advantageous embodiment is characterized in that the setting tool has a means for detecting a capacitance of the capacitor, wherein the one or more control variables comprise the detected capacitance. This makes it possible to compensate for a decrease in capacitance associated with aging of the capacitor. Alternatively or additionally, it is possible to compensate for production fluctuations in capacitance during capacitor manufacture.

[0013] Another particularly advantageous embodiment is characterized in that the setting tool has a means for detecting a mechanical load variable of the setting tool, wherein the one or more control variables comprise the detected mechanical load variable. Preferably, the detected load variable is an acceleration of the setting tool. This makes it possible to adjust the setting energy for subsequent setting processes in the event of over- or under-energy during a setting process.

[0014] Another particularly advantageous embodiment is characterized in that the setting tool has a means for detecting the penetration depth of the fastening element into the substrate, wherein the one or more control variables comprise the detected penetration depth. This makes it possible to readjust the penetration depth for subsequent installation processes in the event of over- or under-energy during a setting process. Preferably, the driving element moves to a reversal position during the conveyance of the fastening element into the substrate and then in the opposite direction, wherein the means for detecting the penetration depth comprises a means for detecting the reversal position of the driving element.

[0015] Another particularly advantageous embodiment is characterized in that the setting tool has a means for detecting a speed of the driving element, wherein the one or more control variables comprise the detected speed. This makes it possible to readjust the setting energy for subsequent setting processes in the event of over- or under-energy during a setting process. Preferably, the means for detecting a speed of the driving element comprises a means for detecting a first point in time at which the driving element passes a first position during its movement toward the fastening element, a means for detecting a second point in time at which the driving element passes a second position during its movement toward the fastening element, and a means for detecting a time difference between the first point in time and the second point in time.

[0016] Another particularly advantageous embodiment is characterized in that the setting tool has a user-adjustable control element, wherein the one or more control variables comprise an adjustment of the control element. Preferably, the control element comprises a dial and / or a slider.

[0017] Another particularly advantageous embodiment is characterized in that the setting tool has a means for detecting a characteristic of the fastening element, wherein the one or more control variables comprise the detected characteristic. This makes it possible to adapt the setting energy to the requirements of the respective fastening element. The characteristic of the fastening element preferably comprises a type and / or an extension and / or a material of the fastening element. Particularly preferably, the characteristic of the fastening element comprises a length and / or a diameter of the fastening element.

[0018] The invention is illustrated in several embodiments in the drawings.

[0019] They show: Fig. 1 a setting tool in a longitudinal section and Fig. 2 a circuit diagram of a setting tool.

[0020] In Fig. 1 A hand-held setting tool 10 for driving fastening elements into a substrate (not shown) is shown. The setting tool 10 has a receptacle 20 designed as a bolt guide, in which a fastening element 30 designed as a nail is received in order to be driven into the substrate along a setting axis A (in Fig. 1 to the left). For feeding fastening elements to the receptacle, the setting tool 10 comprises a magazine 40 in which the fastening elements are stored individually or in the form of a fastening element strip 50 and are gradually transported into the receptacle 20. The magazine 40 has a spring-loaded feed element (not further designated) for this purpose. The setting tool 10 has a driving element 60 which comprises a piston plate 70 and a piston rod 80. The driving element 60 is provided for conveying the fastening element 30 out of the receptacle 20 along the setting axis A into the subsurface. The driving element 60 with its piston plate 70 is guided in a guide cylinder 95 along the setting axis A.

[0021] The driving element 60 is in turn driven by a drive comprising a squirrel-cage rotor 90 arranged on the piston plate 70, an excitation coil 100, a soft-magnetic frame 105, a switching circuit 200, and a capacitor 300 with an internal resistance of 5 mOhm. The squirrel-cage rotor 90 consists of a preferably annular, particularly preferably circular, element with a low electrical resistance, for example made of copper, and is attached to the piston plate 70 on the side of the piston plate 70 facing away from the receptacle 20, for example, soldered, welded, glued, clamped, or positively connected. In embodiments not shown, the piston plate itself is designed as a squirrel-cage rotor.The switching circuit 200 is designed to cause a rapid electrical discharge of the previously charged capacitor 300 and to conduct the resulting discharge current through the excitation coil 100, which is embedded in the frame 105. The frame preferably has a saturation flux density of at least 1.0 T and / or an effective specific electrical conductivity of at most 10 6 S / m, so that a magnetic field generated by the excitation coil 100 is amplified by the frame 105 and eddy currents in the frame 105 are suppressed.

[0022] In a position ready for setting of the driving element 60 ( Fig. 1 ), the driving element 60 with the piston plate 70 is inserted into an unspecified annular recess in the frame 105 such that the squirrel-cage rotor 90 is arranged at a short distance from the excitation coil 100. As a result, an excitation magnetic field, which is generated by a change in an electrical excitation current flowing through the excitation coil, permeates the squirrel-cage rotor 90 and, in turn, induces an annular circulating electrical secondary current in the squirrel-cage rotor 90. This building and thus changing secondary current in turn generates a secondary magnetic field which is opposite to the excitation magnetic field, whereby the squirrel-cage rotor 90 experiences a Lorentz force repelling it from the excitation coil 100, which drives the driving element 60 towards the receptacle 20 and the fastening element 30 received therein.

[0023] The setting tool 10 further comprises a housing 110 in which the drive is accommodated, a handle 120 with an actuating element 130 designed as a trigger, an electrical energy store 140 designed as a rechargeable battery, a control unit 150, a trigger switch 160, a contact pressure switch 170, a means designed as a temperature sensor 180 arranged on the frame 105 for detecting a temperature of the excitation coil 100 and electrical connecting lines 141, 161, 171, 181, 201, 301 which connect the control unit 150 to the electrical energy store 140, the trigger switch 160, the contact pressure switch 170, the temperature sensor 180, the switching circuit 200 and the capacitor 300, respectively. In embodiments not shown, the setting tool 10 is supplied with electrical energy by means of a power cable instead of the electrical energy storage device 140 or in addition to the electrical energy storage device 140.The control unit comprises electronic components, preferably interconnected on a circuit board to form one or more control circuits, in particular one or more microprocessors.

[0024] If the setting tool 10 is placed on a non-shown surface (in Fig. 1 left) is pressed, a pressing element (not further identified) actuates the pressing switch 170, which then transmits a pressing signal to the control unit 150 via the connecting line 171. Triggered by this, the control unit 150 initiates a capacitor charging process, in which electrical energy is conducted via the connecting line 141 from the electrical energy storage device 140 to the control unit 150 and via the connecting lines 301 from the control unit 150 to the capacitor 300 in order to charge the capacitor 300. The control unit 150 comprises for this purpose a switching converter (not further identified) which converts the electrical current from the electrical energy storage device 140 into a suitable charging current for the capacitor 300. When the capacitor 300 is charged and the driving element 60 is in its Fig. 1 The setting tool 10 is in a ready-to-set state when the setting tool is in the position shown. Because the charging of the capacitor 300 is only effected by pressing the setting tool 10 against the substrate, a setting process is only possible when the setting tool 10 is pressed against the substrate, in order to increase the safety of bystanders. In embodiments not shown, the control unit initiates the capacitor charging process as soon as the setting tool is switched on, when the setting tool is lifted from the substrate, or when a previous driving process is completed.

[0025] When the setting tool 10 is ready for use, the actuating element 130 is actuated, for example, by pulling with the index finger of the hand grasping the handle 120, the actuating element 130 actuates the trigger switch 160, which then transmits a trigger signal to the control unit 150 via the connecting line 161. Triggered by this, the control unit 150 initiates a capacitor discharge process, in which electrical energy stored in the capacitor 300 is conducted from the capacitor 300 to the excitation coil 100 by means of the switching circuit 200, thereby discharging the capacitor 300.

[0026] The Fig. 1 The schematically illustrated circuit 200 comprises two discharge lines 210, 220, which connect the capacitor 300 to the excitation coil 200, and of which at least one discharge line 210 is interrupted by a normally open discharge switch 230. The circuit 200 forms an electrical oscillating circuit with the excitation coil 100 and the capacitor 300. Oscillation of this oscillating circuit and / or negative charging of the capacitor 300 may have a negative effect on the efficiency of the drive, but can be prevented with the aid of a freewheeling diode 240. The discharge lines 210, 220 are electrically connected to an electrode 310, 320 of the capacitor 300 by means of electrical contacts 370, 380 of the capacitor 300 arranged on an end face 360 of the capacitor 300 facing the receptacle 20, for example by soldering, welding, screwing, clamping or form-fitting.The discharge switch 230 is preferably suitable for switching a high-current discharge current and is designed, for example, as a thyristor. Furthermore, the discharge lines 210, 220 are spaced closely apart to minimize any parasitic magnetic field induced by them. For example, the discharge lines 210, 220 are combined to form a bus bar and held together by a suitable means, such as a holder or a clamp. In embodiments not shown, the freewheeling diode is electrically connected in parallel with the discharge switch. In further embodiments not shown, no freewheeling diode is provided in the circuit.

[0027] To initiate the capacitor discharge process, the control unit 150 closes the discharge switch 230 via the connecting line 201, causing a high-intensity discharge current from the capacitor 300 to flow through the excitation coil 100. The rapidly rising discharge current induces an excitation magnetic field, which permeates the squirrel-cage rotor 90 and, in turn, induces a circular electrical secondary current in the squirrel-cage rotor 90. This developing secondary current, in turn, generates a secondary magnetic field that opposes the excitation magnetic field, causing the squirrel-cage rotor 90 to experience a Lorentz force repelling the excitation coil 100, which drives the driving element 60 toward the receptacle 20 and the fastening element 30 received therein.As soon as the piston rod 80 of the driving element 60 hits a head (not further specified) of the fastening element 30, the fastening element 30 is driven into the substrate by the driving element 60. Excess kinetic energy of the driving element 60 is absorbed by a braking element 85 made of a resilient and / or damping material, such as rubber, by the driving element 60 moving with the piston plate 70 against the braking element 85 and being decelerated by the braking element 85 until it comes to a standstill. The driving element 60 is then returned to the position ready for installation by a return device (not further specified).

[0028] The capacitor 300, in particular its center of gravity, is arranged behind the driving element 60 on the setting axis A, whereas the receptacle 20 is arranged in front of the driving element 60. With respect to the setting axis A, the capacitor 300 is therefore axially offset from the driving element 60 and radially overlapping with the driving element 60. This allows, on the one hand, a short length of the discharge lines 210, 220 to be achieved, which reduces their resistance and thus increases the efficiency of the drive. On the other hand, a short distance between the center of gravity of the setting tool 10 and the setting axis A can be achieved. This minimizes tilting moments in the event of a recoil of the setting tool 10 during a driving process. In an embodiment not shown, the capacitor is arranged around the driving element.

[0029] The electrodes 310, 320 are arranged on opposite sides of a carrier foil 330 wound around a winding axis, for example by metallizing the carrier foil 330, in particular by vapor deposition, wherein the winding axis coincides with the setting axis A. In embodiments not shown, the carrier foil with the electrodes is wound around the winding axis in such a way that a passage remains along the winding axis. In this case in particular, the capacitor is arranged around the setting axis, for example. The carrier foil 330 has a film thickness of between 2.5 µm and 4.8 µm at a charging voltage of the capacitor 300 of 1500 V, and a film thickness of, for example, 9.6 µm at a charging voltage of the capacitor 300 of 3000 V. In embodiments not shown, the carrier foil is in turn composed of two or more individual foils layered one on top of the other. The electrodes 310, 320 have a sheet resistance of 50 Ohm / □.

[0030] A surface of the capacitor 300 has the shape of a cylinder, in particular a circular cylinder, whose cylinder axis coincides with the setting axis A. The height of this cylinder in the direction of the winding axis is essentially as large as its diameter measured perpendicular to the winding axis. A low height-to-diameter ratio of the cylinder achieves a low internal resistance with a relatively high capacitance of the capacitor 300 and, not least, a compact design of the setting tool 10. A low internal resistance of the capacitor 300 is also achieved by a large conductor cross-section of the electrodes 310, 320, in particular by a high layer thickness of the electrodes 310, 320, whereby the effects of the layer thickness on a self-healing effect and / or a service life of the capacitor 300 must be taken into account.

[0031] The capacitor 300 is mounted on the rest of the setting tool 10 in a dampened manner by means of a damping element 350. The damping element 350 dampens movements of the capacitor 300 relative to the rest of the setting tool 10 along the setting axis A. The damping element 350 is arranged on the end face 360 of the capacitor 300 and completely covers the end face 360. As a result, the individual windings of the carrier foil 330 are evenly loaded by a recoil of the setting tool 10. The electrical contacts 370, 380 protrude from the end face 360 and penetrate the damping element 350. For this purpose, the damping element 350 each has a recess through which the electrical contacts 370, 380 protrude. The connecting lines 301 each have a relief and / or expansion loop (not shown in detail) to compensate for relative movements between the capacitor 300 and the rest of the setting device 10.In embodiments not shown, a further damping element is arranged on the capacitor, for example, on its end face facing away from the receptacle. The capacitor is then preferably clamped between two damping elements, i.e., the damping elements rest against the capacitor with a preload. In further embodiments not shown, the connecting lines have a stiffness that continuously decreases with increasing distance from the capacitor.

[0032] In Fig. 2An electrical circuit diagram 400 of a setting tool (not shown in detail) for driving fasteners into a substrate (not shown) is shown. The setting tool has a housing (not shown), a handle (not shown) with an actuating element, a receptacle (not shown), a magazine (not shown), a driving element (not shown), and a drive for the driving element. The drive comprises a squirrel-cage rotor (not shown) arranged on the driving element, an excitation coil 410, a soft magnetic frame (not shown), a switching circuit 420, a capacitor 430, an electrical energy storage device 440 designed as an accumulator, and a control unit 450 with a switching converter 451 designed, for example, as a direct current transformer (DC / DC converter).The switching converter 451 has a low-voltage side U LV electrically connected to the electrical energy storage device 440 and a high-voltage side U HV electrically connected to the capacitor 430.

[0033] The switching circuit 420 is designed to cause a rapid electrical discharge of the previously charged capacitor 430 and to conduct the resulting discharge current through the excitation coil 410. For this purpose, the switching circuit 420 comprises two discharge lines 421, 422, which connect the capacitor 430 to the excitation coil 420, and of which at least one discharge line 421 is interrupted by a normally open discharge switch 423. A freewheeling diode 424 prevents excessive back-and-forth oscillation of an oscillating circuit formed by the switching circuit 420 with the excitation coil 410 and the capacitor 430.

[0034] When the setting tool is pressed against the ground, the control unit 450 initiates a capacitor charging process in which electrical energy is conducted from the electrical energy storage device 440 to the switching converter 451 of the control unit 450 and from the switching converter 451 to the capacitor 430 to charge the capacitor 430. The switching converter 451 converts the electrical current from the electrical energy storage device 440 at an electrical voltage of, for example, 22 V into a suitable charging current for the capacitor 430 at an electrical voltage of, for example, 1500 V.

[0035] Triggered by actuation of the actuating element (not shown), the control unit 450 initiates a capacitor discharge process, in which electrical energy stored in the capacitor 430 is conducted from the capacitor 430 to the excitation coil 410 via the switching circuit 420, thereby discharging the capacitor 430. To initiate the capacitor discharge process, the control unit 450 closes the discharge switch 430, causing a high-intensity discharge current from the capacitor 430 to flow through the excitation coil 410. As a result, the squirrel-cage rotor (not shown) experiences a Lorentz force repelling it from the excitation coil 410, which drives the driving element. The driving element is then returned to a position ready for insertion by a reset device (not shown).

[0036] The amount of energy of the current flowing through the excitation coil 410 during the rapid discharge of the capacitor 430 is controlled by the control unit 450, in particular continuously by setting a charging voltage (U HV ) applied to the capacitor 430 during and / or at the end of the capacitor charging process and before the start of the rapid discharge. The electrical energy stored in the charged capacitor 430 and thus also the amount of energy of the current flowing through the excitation coil 410 during the rapid discharge of the capacitor 430 are proportional to the charging voltage and can therefore be controlled by means of the charging voltage. The capacitor is charged during the capacitor charging process until the charging voltage U HV has reached a target value. The charging current is then switched off. If the charging voltage decreases before the rapid discharge, for example due to parasitic effects, the charging current is switched on again until the charging voltage U HV has reached the target value again.

[0037] The control unit 450 controls the amount of energy of the current flowing through the excitation coil 410 during the rapid discharge of the capacitor 430 as a function of several control variables. For this purpose, the setting tool comprises a means, designed as a temperature sensor 460, for detecting a temperature of the excitation coil 410 and a means for detecting a capacitance of the capacitor, which is designed, for example, as a calculation program 470 and calculates the capacitance of the capacitor from a current intensity and an electrical voltage of the charging current during the capacitor charging process. Furthermore, the setting tool comprises a means, designed as an acceleration sensor 480, for detecting a mechanical load variable of the setting tool.The setting tool further comprises a means for detecting the depth of penetration of the fastening element into the substrate, which comprises, for example, an optical, capacitive, or inductive proximity sensor 490, which detects a reversal position of the driving element (not shown). Furthermore, the setting tool comprises a means for detecting the speed of the driving element, which comprises a means configured as a first proximity sensor 500 for detecting a first point in time at which the driving element passes a first position during its movement toward the fastening element, a means configured as a second proximity sensor 510 for detecting a second point in time at which the driving element passes a second position during its movement toward the fastening element, and a means configured as a calculation program 520 for detecting a time difference between the first point in time and the second point in time.Furthermore, the setting tool comprises an operating element 530 that can be adjusted by a user and a means designed as a barcode reader 540 for detecting a characteristic value of a fastening element to be driven.

[0038] The control variables, as a function of which the control unit 450 controls the amount of energy of the current flowing through the excitation coil 410 during the rapid discharge of the capacitor 430, include the temperature detected by the temperature sensor 460 and / or the capacitance of the capacitor calculated by the calculation program 470 and / or the load value of the setting tool detected by the acceleration sensor 480 and / or the driving depth of the fastening element detected by the proximity sensor 490 and / or the speed of the driving element calculated by the calculation program 520 and / or the setting of the operating element 530 set by the user and / or the characteristic value of the fastening element detected by the barcode reader 540.

[0039] The invention has been described using a number of exemplary embodiments, some of which are shown in the drawings and some of which are not shown. The individual features of the various exemplary embodiments can be used individually or in any combination, provided they do not contradict one another. It should be noted that the setting tool according to the invention can also be used for other applications.

Claims

1. Setting tool (10) for driving fastening elements into a substrate, in particular a handheld setting tool, comprising a receptacle (20) which is intended to receive a fastening element (30), a driving element which is intended to convey a fastening element received in the receptacle along a setting axis into the substrate, a drive which is intended to drive the driving element (60) along the setting axis toward the fastening element, wherein the drive comprises an electrical capacitor (300), a squirrel-cage rotor (90) arranged on the driving element, and an excitation coil (100) through which current flows during a rapid discharge of the capacitor and which generates a magnetic field which accelerates the driving element toward the fastening element, characterized in that the setting tool comprises a control unit (150, 450) which is suitable for controlling an amount of energy of the current flowing through the excitation coil during the rapid discharge of the capacitor depending on one or more control variables.

2. Setting tool according to claim 1, wherein the capacitor is charged with a charging voltage at the beginning of the rapid discharge, and wherein the control unit (150) is suitable for controlling the charging voltage.

3. Setting tool according to any of the preceding claims, wherein the setting tool comprises a means (180) for detecting a temperature of an environment and / or of the setting tool, in particular of the excitation coil, and wherein the one or more control variables comprise the detected temperature.

4. Setting tool according to claim 3, wherein the higher a charging voltage of the capacitor, the higher the detected temperature.

5. Setting tool according to any of the preceding claims, wherein the setting tool comprises a means (470) for detecting a capacitance of the capacitor, and wherein the one or more control variables comprise the detected capacitance.

6. Setting tool according to any of the preceding claims, wherein the setting tool comprises a means (480) for detecting a mechanical load variable of the setting tool, in particular an acceleration of the setting tool, and wherein the one or more control variables comprise the detected mechanical load variable.

7. Setting tool according to any of the preceding claims, wherein the setting tool comprises a means (490) for detecting a driving depth of the fastening element into the substrate, and wherein the one or more control variables comprise the detected driving depth.

8. Setting tool according to claim 7, wherein the driving element moves to a reversing position during the conveyance of the fastening element into the substrate and thereafter in the opposite direction, and wherein the means for detecting the driving depth comprises a means for detecting the reversing position of the driving element.

9. Setting tool according to any of the preceding claims, wherein the setting tool comprises a means (500) for detecting a speed of the driving element, and wherein the one or more control variables comprise the detected speed.

10. Setting tool according to claim 9, wherein the means for detecting a speed of the driving element comprises a means for detecting a first point of time at which the driving element passes a first position during its movement toward the fastening element, a means for detecting a second point of time at which the driving element passes a second position during its movement toward the fastening element, and a means for detecting a time difference between the first point of time and the second point of time.

11. Setting tool according to any of the preceding claims, wherein the setting tool comprises an operating element (530) which is adjustable by a user, and wherein the one or more control variables comprise an adjustment of the operating element.

12. Setting tool according to claim 11, wherein the operating element comprises an adjustment wheel and / or a slider.

13. Setting tool according to any of the preceding claims, wherein the setting tool comprises a means (540) for detecting a characteristic variable of the fastening element, and wherein the one or more control variables comprise the detected characteristic variable.

14. Setting tool according to claim 13, wherein the characteristic variable of the fastening element comprises a type and / or an extension, in particular a length and / or a diameter, and / or a material of the fastening element.