DE102011003009A1 - Processing machine for producing tear line in airbag cover, has fourth linear guide unit that is attached with tool head and connected to control unit for controlling movement of tool along specific axis - Google Patents

Abstract

The machine (2) has three linear guide units (12,14,16,18,20) that move a tool head (22) along the X-axis, Y-axis and Z-axis respectively. A control unit is connected to the linear guide units for controlling movement of the tool head along a desired trajectory in space. A fourth linear guide unit (26) is attached with tool head and connected to control unit for controlling movement of the tool (24) along a ZB-axis. An independent claim is included for method for generating weakening line in plastic component.

Description

The invention relates to a processing machine for guiding a tool along a trajectory in space, and a tool head for such a processing machine and a method for generating lines of weakness in plastic components with such a processing machine or such a tool head.

Processing machines for guiding a tool along a trajectory in space are known, see, for example, the DE 199 04 050 C2 , the DE 44 41 252 A1 or that DE 80 22 759 U1 ,

Such processing machines comprise a tool head, the respective tool, for. A router, carries first, second and third linear guide means for moving the tool head along first, second and third major axes (X-axis, Y-axis and Z-axis) and control means connected to the linear guide means to move the tool head controlled along a desired trajectory in space.

Due to the three linear guide devices, the movement of the tool head is given in a Cartesian coordinate system with the three mutually perpendicular main axes, wherein the mutually perpendicular X and Y axes may span a horizontal plane and the Z-axis may be perpendicular thereto and thus vertically ,

The storage, suspension, guidance, etc. of the tool head along the three main axes can be done here, for example, in the so-called gantry design or portal construction. These designs are well known in the field of processing or machine tools, so that can be dispensed with detailed description of the relevant design features and principles of action here.

The movement of the tool head along the Z-axis, ie a vertical movement in accordance with the above definition, causes a feed movement of the tool head and thus of the machining tool received herein to a workpiece located below the tool head or a lifting movement away from the workpiece. The movement mechanism in the (third) linear guide means for moving the tool head along the third major axis (Z-axis) has to carry, in addition to all or a substantial part of its own weight, the weight of the tool head and the tool received therein, these weights being along Z. Direction, ie in the vertical direction, with high speed on the one hand and high precision on the other hand must be moved. However, high speeds of movement in the direction of the Z-axis on the one hand and high-precision positioning of the tool head or the tool relative to the workpiece on the other hand so far out or are difficult to reconcile, as required accuracies in the micrometer range end positions of the tool head and the tool can not be approached quickly relative to the workpiece. High inertia forces would induce vibration or dithering movements during fast movements, which would not be tolerable in view of the required manufacturing accuracies.

It is therefore necessary to move the tool head correspondingly slowly in the case of high-precision machining operations, in particular to decelerate with a correspondingly flat deceleration curve when approaching the machining end position and to stop it in order to avoid undesired vibrations. Particularly in the case of complex machining operations in which the tool head has to be lifted several times from the workpiece during the machining of a single workpiece and has to be delivered precisely again, the comparatively long times, in particular the infeed movements, which are absolutely necessary due to the flat deceleration curve, disadvantageously add up. so that the throughput decreases disadvantageously.

The invention has the object, on the other hand, to design a processing machine of the type in question so that an increased workpiece throughput is possible with this machine without sacrificing the quality of processing. It is another object of the present invention to provide a tool head for such a processing machine or for a multi-axis robot and it is an object of the invention to provide a method for producing lines of weakness in plastic parts and in particular of tear lines in airbag covers.

To achieve these objects, the present invention proposes that the tool head has a fourth linear guide device for controlled movement of the tool along a fourth axis, this fourth linear guide device being connected to the control device.

The subject matter of the present invention thus provides a fourth linear guide device, which is arranged on the tool head, which in turn is moved by the third linear guide device. The fourth linear guide device is able to move the tool controlled along a fourth axis, wherein these Control is carried out by the control device which is connected to the fourth linear guide device.

The fourth linear guide device must therefore carry only its own weight or a part thereof, as well as the weight of the respective tool and move along the fourth axis, and here in particular accelerate, decelerate and stop in a movement along the fourth axis. Due to the lower mass, which is to be moved by the fourth linear guide device, in particular to accelerate and decelerate, movements along the fourth axis are much faster feasible. It follows that with the processing machine according to the invention more workpieces per unit time are editable, so the workpiece throughput is increased.

According to an advantageous embodiment, the tool head is a milling head which carries a rotating milling tool and which has a first rotary drive for rotating the milling tool about a first axis of rotation. Since this is only an advantageous embodiment of the present invention, the processing machine according to the invention is not limited to a milling head as a tool head, but can equally be equipped with other tool heads, in particular, but not exclusively, those for a machining operation.

A further preferred embodiment of the present invention provides that the fourth axis is parallel to the third main axis. If the third main axis is defined as vertical Z-axis according to the above definition, the fourth axis is also vertical. In a particularly advantageous manner, therefore, equally fast and precise feed movements of the tool head to the workpiece can take place in the vertical Z direction.

Further preferably, the fourth axis may also be parallel to the first axis of rotation of the milling tool.

The maximum stroke of the fourth linear guide device is preferably smaller than the maximum stroke of the third linear guide device. As a result, the cost of materials for forming the linear guide device and thus its weight is reduced in the region of the fourth linear guide device. This in turn makes even faster movements of the fourth linear guide device while maintaining the required high precision possible.

The processing machine according to the invention may further comprise a second, connected to the control device rotary drive, which is provided for inclining the milling tool together with the fourth linear guide device about a second axis of rotation. By introducing this second axis of rotation, the degrees of freedom increase during machining. In this embodiment, the above-mentioned parallelism of the third and fourth axis one of a plurality of positions of the two axes to one another in the context of Verschwenkungswegs the milling tool to the second axis of rotation.

Furthermore, the processing machine according to the invention may have a third, connected to the control device rotary drive for rotating the milling head about a third axis of rotation. As a result, a further increase in the achievable degrees of freedom is possible.

The processing machine further preferably has a holding device for fixing a workpiece to be processed. Depending on the workpiece to be machined, this holding device may be designed differently or optimized, so it may for example be a simple clamping table, a Umbugvorrichtung, a vacuum table or the like. The processing machine according to the invention can be designed, for example, in a manner known per se in a gantry design or even a portal construction.

The subject of the present invention is furthermore a tool head with a machining tool, which is integrated in particular in a processing machine according to the invention. The tool head comprises a drive for the machining tool, a linear guide device for controlled movement of the tool head along an axis and an interface for controlling the linear guide device via the control device of the processing machine. This tool head can also be placed on a known multi-axis robot with at least 3 axes of rotation. Multi-axis robots are universally applicable, but have the disadvantage that even with a linear movement of the tool all axes of rotation must be controlled. If such multi-axis robot z. B. used in generating attenuation lines in valve parts, the use of the tool head according to the invention also leads to reduced processing times, since "small" linear movements can be done with the linear guide device of the tool head.

According to a preferred embodiment, in this case the machining tool is a milling tool and the drive is a first rotary drive for rotating the milling tool about a first axis of rotation, wherein the linear guide means moves the milling tool along an axis which is parallel to the first axis of rotation.

In this case, a second rotary drive connected to the interface may preferably be provided for tilting the milling tool and the linear guide device about a second axis of rotation. Furthermore, a third, connected to the interface rotary drive for rotating the milling head can be provided about a third axis of rotation.

The present invention furthermore relates to a method for producing lines of weakness in plastic components and, more particularly, to a method for producing tear lines in airbag covers, in particular with a processing machine and / or a tool head according to the present invention. The lines of weakness are in this case milled in particular in the plastic component. The formation of weakening lines in plastic components is for example from the DE 100 42 264 A1 or even the DE 199 44 371 A1 known. In a particularly advantageous manner, this known approach can be combined with the processing machine according to the present invention, since the required in this processing high-precision control of the tool head is ensured, the throughput is increased.

Further details, aspects and advantages of the present invention will become more apparent from the following description with reference to the drawing.

It shows:

1 in a schematically greatly simplified representation of an embodiment of a processing machine according to the invention; and

2 an enlarged view of the fourth linear guide device with thereto arranged tool head from the direction of the arrow II in 1 , wherein the fourth linear guide device is shown in two relative positions to a holder.

In the figure is a total with 2 designated processing machine shown, which in the illustrated embodiment has a so-called gantry design, in which all three axes of motion associated with a movable machine portal and a workpiece 4 on a rigid or fixed table 6 is arranged. The machine portal essentially comprises two lateral supports or stands 8th and 10 between which the table 6 is arranged. At their upper free ends carry the stands 8th and 10 by means of unspecified storage facilities 12 and 14 , which are formed as out of the plane or in this extending longitudinal or linear guides, one the side stand 8th and 10 spanning carrier 16 , On the carrier 16 is via a further, not shown linear guide device a carriage 18 stored along the longitudinal extent of the carrier 16 and thus between the two stands 8th and 10 is movable.

At the sled 18 is a holder also not shown linear guide means 20 stored, with respect to the carriage 18 along another main axis (in the drawing from top to bottom or from bottom to top) is adjustable.

At its lower end in the drawing is on the holder 20 a tool head 22 arranged to receive a tool 24 serves.

The movement of the carrier 16 relative to the uprights 8th and 10 is defined as a movement along the X-axis; the movement of the sled 18 along the carrier 16 is defined as a movement along the Y-axis and the movement of the holder 20 concerning the sled 18 is defined as a movement along the Z-axis. In this case, furthermore, the X-axis is defined as the first main axis, the Y-axis as the second main axis and the Z-axis as the third main axis.

The tool head 22 and with it the tool 24 can by appropriate movements of carrier 16 , Sledges 18 and holder 20 the tool 24 be moved along a desired trajectory in Cartesian space.

The controls of the respective linear guide means or linear guide means or the associated actuators via a preferably central control device or user / machine interface.

The tool 24 be in the illustrated embodiment, a milling tool, with which the workpiece 4 is editable, in particular by means of the carrier 16 and the sled 18 Traversing movements take place in the X / Y plane and over the holder 20 Infeed movements of the tool head and thus of the tool 24 in the direction of the Z axis, ie on the workpiece 4 take place to or from this.

At the processing machine 2 According to the present invention, the tool head 22 indirectly at the lower end of the holder 20 by a fourth linear guide device 26 appropriate. The fourth linear guide device 26 can do the tool head 22 controlled along a fourth axis ZB relative to the holder 20 to move.

In one possible embodiment, this is the fourth linear guide device 26 opposite the holder 20 insofar rigid, as the fourth axis ZB is parallel to the third main axis, ie the Z-axis.

The tool 24 can rotate about a rotation axis DA, which may also be parallel to the fourth axis ZB and / or third main axis Z. In the area of the tool head 22 and / or the fourth linear guide device and / or the lower end of the holder 20 can be arranged rotary actuators with which further rotational and / or pivotal movements of individual modules to each other are possible to the tool 24 to give additional degrees of freedom. Thus, the tool may be particularly preferred 24 together with the fourth linear guide device 26 be rotated about an axis A, which is substantially perpendicular to the axis ZB and / or the axis Z. This results in approximately according to 2 the possibility of the unit consisting of fourth linear guide device 26 and this adjustable tool head 22 along a curve K one and / or both sides to pivot, ie in 2 in and / or counterclockwise. The parallelism of the fourth linear guide device 26 opposite the holder 20 , Thus, the fourth axis ZB to the third main axis (Z-axis) is thus only one of a plurality of layers.

Furthermore, optionally by means of a further rotary drive of the tool head 22 be rotated about a rotation axis C, which is either aligned with the axis of rotation of the tool 24 on the tool head 22 is or radially to this, that is offset eccentrically. This further rotary drive is not shown in detail in the drawing. In particular, the formation of the further rotary drive is such that according to the drawings of the holder 20 is executed in two parts and thus essentially from an upper part 20a attached to the holder 18 is arranged and a lower part 20b is constructed, on which the fourth linear guide device 26 is arranged. In the area of a parting plane 20c are the two parts 20a and 20b rotatable relative to each other and preferably in the counterclockwise direction by the further rotary drive, wherein the axis A, with the fourth linear guide device 26 on the holder 20 or its lower part 20b is struck, with a rotation of the lower part 20b opposite the upper part 20a with being twisted. In the 2 indicated pivotability of the fourth linear guide device 26 opposite the holder 20 is thus possible within a radius of up to 360 °.

The other rotary actuators are also connected to the common control device.

The stroke of the fourth linear guide device 26 along the axis ZB is the subject of the processing machine according to the invention 2 preferably smaller than the stroke of the third linear guide device, with which the holder 20 along the Z-axis is movable. Not least from this it follows that the fourth linear guide device 26 opposite the holder 20 has a much lower mass (less material required by linear bearings, smaller drive motors, etc.), so that with it the tool head 22 and with it the tool 24 can be moved much faster, in particular faster towards a desired position of the tool 24 relative to the workpiece 4 procedure and can be stopped there vibration-free.

It is essential here that the third linear guide device for moving the holder 20 and thus the tool head 22 along the third major axis (Z-axis) has the same accuracy as the fourth linear guide device 26 with which the tool head 22 and ultimately the tool 24 is movable. The third linear guide device is therefore not to be understood as a coarse positioning device and the fourth linear guide device 26 not as fine positioning device, since both guide devices or their actuators have the same accuracy. The difference between the third linear guide device for the holder 20 and the fourth linear guide device 26 for the tool head 22 is according to the invention substantially in that the fourth linear guide device 26 can be moved significantly faster and still vibration-free, especially with respect to the holder 20 significantly steeper acceleration and deceleration curves, as the masses to be moved turn out smaller.

The maximum movement or stroke of the fourth linear guide device 26 can be compared to those of the owner 20 for example, by a factor 20 be reduced so that, for example, at a maximum stroke of the holder 20 of 1000 mm the fourth linear guide device 26 a maximum stroke of 50 mm. From this and from the lower masses to be moved, much higher actuating speeds result with steeper acceleration and deceleration curves for the tool head 22 and with it the tool 24 , The actual stroke is typically smaller than the maximum stroke and is optimized by the controller for low processing time. By the control device, the current stroke of the fourth linear guide device 26 depending on the workpiece to be machined and adjusted depending on the respective position on this workpiece. The fourth linear guide device is completely integrated into the control by the control device (not shown).

In summary, this results in higher throughput rates as the respective desired positions of the tool 24 relative to the workpiece 4 can be approached much faster while maintaining the required accuracy.

It is understood that the subject matter of the present invention is not limited to the illustrated embodiment. Thus, while achieving the same advantages, the present invention can also be applied to a gantry machine. Furthermore, the design of the tool 24 As a milling tool to understand as not limiting, but there are other cutting or non-cutting machining tools used. The tool head according to the invention can also be used on an industrial robot known per se, ie z. B. a multi-axis robot with at least three axes.

A machine tool has been described for guiding a tool along a path in space, with a tool head carrying the respective tool, a first linear guide device for moving the tool head along a first main axis (X-axis); a second linear guide means for moving the tool head along a second major axis (Y-axis); a third linear guide means for moving the tool head along a third major axis (Z-axis); and a controller connected to the linear guide means for controlled movement of the tool head along a desired trajectory in space. The tool head has a fourth linear guide device for controlled movement of the tool along a fourth axis (ZB axis) and the control device is connected to this fourth linear guide device. The stroke of the fourth linear guide device is preferably smaller than the stroke of the third linear guide device. The workpiece throughput can be increased by higher processing speeds due to lower moving masses. The tool is preferably a milling tool for producing at least one line of weakness in a plastic component and in particular for generating tear lines in airbag covers.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19904050 C2 [0002]
• DE 4441252 A1 [0002]
• DE 8022759 U1 [0002]
• DE 10042264 A1 [0022]
• DE 19944371 A1 [0022]

Claims (16)

Processing machine for guiding a tool ( 24 ) along a trajectory in space, with - a tool head ( 22 ), the respective tool ( 24 ), - a first linear guide device ( 16 . 18 ) for moving the tool head ( 22 ) along a first major axis (X-axis); A second linear guide device ( 12 . 14 . 16 ) for moving the tool head ( 22 ) along a second major axis (Y-axis); A third linear guide device ( 18 . 20 ) for moving the tool head ( 22 ) along a third major axis (Z-axis); and - a control device, which is connected to the linear guide devices, for the controlled movement of the tool head ( 22 ) along a desired trajectory in space, characterized in that the tool head ( 22 ) a fourth linear guide device ( 26 ) for the controlled movement of the tool ( 24 ) along a fourth axis (ZB axis), and that the control device with the fourth linear guide device ( 26 ) connected is. Processing machine according to claim 1, characterized in that the tool head ( 22 ) is a milling head, which is a rotary milling tool ( 24 ) and which has a first rotary drive for rotating the milling tool about a first axis of rotation (DA). Processing machine according to claim 1 or 2, characterized in that the fourth axis (ZB-axis) is parallel to the third main axis (Z-axis). Processing machine according to claim 2 or 3, characterized in that the fourth axis (ZB axis) parallel to the first axis of rotation (DA) of the milling tool ( 24 ) lies. Processing machine according to one of the preceding claims, characterized in that the maximum stroke of the fourth linear guide device ( 26 ) is smaller than the maximum stroke of the third linear guide device ( 18 . 20 ). Processing machine according to one of the preceding claims, characterized by a second, connected to the control device rotary drive for inclining the milling head and the fourth linear guide device ( 26 ) about a second axis of rotation (A-axis). Processing machine according to one of the preceding claims, characterized by a third, connected to the control device rotary drive for rotating the milling head about a third axis of rotation (C-axis). Processing machine according to one of the preceding claims, characterized by a holding device ( 6 ) for fixing a workpiece to be machined ( 4 ). Processing machine according to one of the preceding claims, characterized in that it is designed in gantry design. Processing machine according to one of the preceding claims 1 to 8, characterized in that it is designed in portal construction. Tool head with a machining tool ( 24 ), in particular for a processing machine ( 2 ) according to one of the preceding claims, with - a drive for the machining tool ( 24 ), - a linear guide device ( 26 ) for the controlled movement of the milling tool ( 24 ) along an axis (ZB axis), and - an interface for driving the linear guide device ( 26 ). Tool head according to claim 11, characterized in that the machining tool ( 24 ) is a milling tool and the drive is a first rotary drive for rotating the milling tool ( 24 ) about a first axis of rotation (DA), wherein the linear guide device ( 26 ) the milling tool ( 24 ) is moved along an axis parallel to the first axis of rotation (DA). Tool head according to claim 11 or 12, characterized by a second, connected to the interface rotary drive for inclining the milling tool ( 24 ) and the linear guide device ( 26 ) about a second axis of rotation (A-axis). Tool head according to one of the preceding claims 11 to 13, characterized by a third, connected to the interface rotary drive for rotating the tool head about a third axis of rotation (C-axis). Method for producing at least one weakening line in a plastic component, in particular with a processing machine ( 2 ) according to one of the preceding claims 2 to 10 or with a tool head according to one of the preceding claims 11 to 14, characterized in that the weakening line is milled into the plastic component. A method according to claim 15, characterized in that the generated lines of weakness are tear lines in airbag covers.

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