Fixing device, machining head, machine tool and method for fixing a workpiece

Abstract

The present disclosure relates to a fixing device arranged to be fastened to a machining head such as a drill head. A machine tool for machining workpieces such as metal sheets at a machining point is also disclosed. The workpieces may be machined from a machining side. A fastening device is included and adapted for fastening the fixing device to the machining head. A fixing head is included and adapted for releasably, locally fixing the workpiece on its machining side and adjacent to the machining point. A controller is included and configured to control the fixing and releasing of the fixing head on a workpiece.

Claims

1. A method for fixing a workpiece during machining by at least one of a machining head and a drill head of a machine tool, wherein the workpieces are machined from a machining side at a machining point, the method comprising the steps: fixing the workpiece, relative to the machining head, on the machining side of the workpiece and adjusting the machining point by means of a fixing device comprising: a fastening device adapted for fastening the fixing device to the machining head; a fixing head adapted for releasably, locally fixing the workpiece on the machining side thereof and adjacent to the machining point by exerting a holding force which is directed to the fixing device and to the machining head; and a controller configured to control the fixing and releasing of the fixing head on the workpiece, when a control command is given, wherein the fixing is realized by exerting a holding force which is directed to the fixing device and to the machining head; machining the workpiece at the machining point by the machining head; removing at least one of dirt and residues resulting from the machining from the machining side of the workpiece by at least one of suctioning and extracting device with at least one compressed air inlet; and releasing the workpiece from the fixing device when a control command is given.

2. The method according to claim 1, wherein the fixing device is configured to apply an attractive force to the machining side of the workpiece to fix the workpiece with its machining side at the fixing head.

3. The method according to claim 1, further comprising the steps of at least one of blowing any dirt away and extracting any dirt away, at least before an activation of the fixing device and the fixing of the workpiece.

4. The method according to claim 1, wherein, at least during machining, residues occurring during machining are extracted and/or lubricant and/or coolant is injected.

5. The method according claim 1, further comprising the steps of detecting the presence of a tool by means of a sensor.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) Further advantages features and details of the various embodiments of this disclosure will become apparent from the ensuing description of a preferred exemplary embodiment or embodiments and further with the aid of the drawings. The features and combinations of features recited below in the description, as well as the features and feature combination shown after that in the drawing description or in the drawings alone, may be used not only in the particular combination recited but also in other combinations on their own without departing from the scope of the disclosure.

(2) The invention will be explained below in exemplary embodiments with reference to the accompanying drawings. In the figures:

(3) FIG. 1 depicts a schematic side view in partial section of a machining head and a fixing device;

(4) FIG. 2 depicts a schematic bottom view in partial section of a fixing device;

(5) FIG. 3 depicts a further schematic side view in partial section of a machining head and a fixing device;

(6) FIG. 4 depicts a schematic perspective view of a machine tool; and

(7) FIG. 5 depicts a flow chart of a method for fixing a workpiece.

DETAILED DESCRIPTION OF THE INVENTION

(8) As used throughout the present disclosure, unless specifically stated otherwise, the term “or” encompasses all possible combinations, except where infeasible. For example, the expression “A or B” shall mean A alone, B alone, or A and B together. If it is stated that a component includes “A, B, or C”, then, unless specifically stated otherwise or infeasible, the component may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C. Expressions such as “at least one of” do not necessarily modify an entirety of the following list and do not necessarily modify each member of the list, such that “at least one of “A, B, and C” should be understood as including only one of A, only one of B, only one of C, or any combination of A, B, and C.

(9) FIG. 1 shows a schematic side view in partial section of a fixing device 100, which is fastened to a machining head 200 for machining a workpiece 300, here in the form of a metal sheet.

(10) The machining head 200 is designed here as a drill head with a drill 210. The drill 210 is fastened to a spindle 220 which is movable along the Z axis, i.e., vertically. The machining head 200 is arranged here above the workpiece 300. Thus, the drill 210 can machine the workpiece 300 from a machining side 310, which in this example corresponds to the top of the workpiece 300.

(11) The fixing device 100 comprises a fixing head 110, which is fastened to the machining head 200 by means of a fastening device 120. The fixing head 110 is used for releasable, local fixing of the workpiece 300 on the machining side 310 of the workpiece 300.

(12) The fixing is achieved by a holding force H, which is directed upwards here, i.e., to the fixing device 100 and to the machining head 200. Thus, a fixing can be independent of the other support of the workpiece 300. Pressing frictional forces can therefore be dispensed with. Rather, an attractive force, such as a vacuum or a magnet is used.

(13) For fixing the workpiece 300, the fixing device 100 comprises a vacuum suctioning device 130, which is designed here in the form of a suction cup or comprises a plurality of suction cups. A controller, not shown here, controls the fixing and releasing of the fixing head 110 by corresponding actuation of the vacuum holder 130. The vacuum holder 130 is used for locally fixing the workpiece 300 in the region of a machining axis A of the machining head 200. Depending on the thickness of the workpiece, this area has a radius of 0.5 to ten centimetres around a machining point which lies at the intersection of the machining axis A with the workpiece 300. This fixing counteracts the force which is applied by the tool, here in the form of the drill 210, to the machining side 310 of the workpiece 300.

(14) In addition to the main function of fixing, the fixing device 100 or the fixing head 110 can comprise further functions. For example, a suctioning and/or extracting device can be provided with at least one compressed air inlet 140 to remove dirt and/or residues resulting from machining, for example such as shavings, from the machining side 310 of the workpiece 300. The shavings carried along with the air are removed via an air outlet 150. In addition, a collar 160 can be provided which shields the machining space and around the drill 210, so that the air and the shavings are carried away only through the air outlet 150. The collar 160 can be flexible or telescopically movable to accommodate the movement of the spindle 220 in the Z direction.

(15) Furthermore, a sensor 170 can be provided for detecting the presence of a tool. This sensor is designed as a photoelectric barrier in this example. Thus, among other things, with a known position along the Z axis, the length of the tool, here the drill 210, can be determined. For example, the wear can be determined, or the positioning accuracy can be increased.

(16) Furthermore, an adjustable or movable counter-bearing 190 can be provided on the fixing head 110, which can be moved on an edge of the workpiece 300 with a movement device 192 to bear on the side of the workpiece 300 facing away from the machining side 310. The counter-bearing 190 can include a metal profile or an angle. The movement device 192 can include a cylinder 194, with which the counter-bearing 190 is movable in the Z direction. In this case, the counter-bearing 190 in a guide 196 can be movable, e.g., liftable, as shown in FIG. 1. When the counter-bearing 190 is not used, it is retracted into the guide 196 to ensure maximum freedom of movement of the fixing head 110 or of the machining head 200.

(17) The counter-bearing 190 and the moving device 192 are shown only schematically. Both elements are arranged on the fixing head 110 and therefore move together therewith or with the machining head 200.

(18) Optionally, the moving device 192 can include a pivot unit (not shown) with which the counter-bearing 190 can at least partially move or pivot the workpiece 300 under, i.e., opposite the machining side 310. In the absence of further support from below, the counter-bearing 190 then serves as a counter-bearing in this area and supports the fixing by the at least one vacuum holder 130. The workpiece 300 at least partially rests on a leg of the counter-bearing 190.

(19) FIG. 2 shows a view from below in a partial sectional view of the fixing device 100 with the fixing head 110. It can be seen that in this embodiment a plurality of vacuum holders 130, here in the form of suction cups, are arranged distributed around the machining axis A.

(20) A plurality of compressed air inlets 140 are distributed around the central machining axis. These compressed air inlets 140 are arranged such that they generate an airflow L circulating around the central machining axis A in the direction of the air outlet 150. In addition, the compressed air inlets 140 can be formed to be funnel-shaped, wherein the opening angle of the funnel is greater in the direction of the air flow L to be generated. Ideally, the air flow L circulates in the direction of the rotational movement of the tool. The compressed air inlets 140 are connected to each other via an air channel 142, via which the compressed air is supplied.

(21) The sensor 170, which is designed here as light barriers which are arranged diametrically to each other with respect to the central machining axis A. This ensures that the tool is reliably detected whilst approaching the machining side 310 of the workpiece 300.

(22) Furthermore, the fixing head 110 or the fixing device 100 comprises an injection nozzle 180 with which lubricant and/or coolant for the tool can be injected in the direction of the central machining axis A. In this way, among other things, the wear on the tool can be minimised and the quality of the machining can be increased.

(23) FIG. 3 shows a further schematic side view in partial section of the fixing device 100 with the fixing head 110, which is fastened to the machining head 200 for machining the workpiece 300. For reasons of clarity, the fastening device for fastening the fixing device 100 to the machining head 200 is not shown here.

(24) The two vacuum holders 130 are activated and accordingly fix the machining side 310 in position relative to the machining head 200. Via a vacuum connection 132, which is in communication with the two vacuum holders 130, the vacuum is built up in the two vacuum holders 130.

(25) The compressed air inlet 140 is connected via the air channel 142 with a compressed air connection 144. Both the vacuum port 132 and the compressed air port 144 can be connected to corresponding ports of the machining head 200. The air outlet 150 can also be connected to 100 via a corresponding hose, for example. In this way, the fixing head 110 is not only fastened to the machining head 200 but is also completely supplied with power thereby. Likewise, the power supply for the fixing head 110 can originate from the machining head 200. The power supply can be provided for example for the supply of the sensor 170, the injection nozzle 180, the operation of possibly provided valves for the vacuum and/or the compressed air as well as for the controller. This allows the fixing device 100 to be formed integrally with the machining head 200. Thus, the fixing device 100 can be easily moved with the machining head 200.

(26) FIG. 4 shows a schematic perspective view of a machine tool 400 with a machining head 200 for machining a workpiece 300. The fixing device 100 is arranged on the machining head 200. The machining head 200 is arranged on a bridge 420 that can be moved in the X- and Y-directions. Thus, the fixing device 100 travels together with the machining head 200.

(27) The workpiece 300 is mounted on a structure such as a movable table 410. The table 410 supports the workpiece 300 only selectively or in sections. In the area of the machining axis, the fixing device holds or fixes the machining side of the workpiece in position locally despite the absence of support from below. This improves the quality of the machining and reduces the wear on the tool.

(28) FIG. 5 shows a flow chart of a method for fixing a workpiece during machining by a machining head, in particular a drill head, of a machine tool wherein the workpieces are machined from a machining side at a machining point.

(29) In a first step 500, the workpiece is fixed or attached on the machining side of the workpiece and adjacent to the machining point relative to the machining head by means of a fixing device, in particular the fixing device as described above, when a control command is given. The fixing takes place by activating the vacuum holder. The control command can be given by the controller of the machine tool or by the sensor which detects the lowering tool. Thus, the length of the tool can also be detected with a known position in the Z direction. This information can be used, for example, for the maintenance status of the tool, for example to determine the time of replacement of the tool. At least before the activation of the fixing device and the fixing of the workpiece, any dirt that might be present can be extracted or blown away using the suctioning and/or extracting device.

(30) In a second step 510, the workpiece is machined at the machining point by the machining head. During machining, any residues such as shavings can be extracted. In addition, lubricant and/or coolant can be injected to the location of the machining.

(31) In a third step 520, the workpiece is released again when a control command is given. The control command can be given by the controller of the machine tool or by the sensor which detects the raising tool.

(32) These steps can be repeated for further machining steps on the workpiece. Then a movement of the machining head and/or the workpiece takes place between these steps. During the method process, the extracting device can remain activated for the residues created during machining.

(33) The fixing device presented here holds the machining side of the workpiece in the region of the machining axis locally in the absence of support from below. This improves the quality of the machining and reduces the wear on the tool.