DE102010008998B4 - Device for processing a plastic workpiece - Google Patents

Abstract

The invention relates to a device for processing a plastic workpiece with a robot device (10) which can preferably be actuated via a plurality of movement axes, on the robot arm of which a processing device (16) is provided for processing the plastic workpiece, the processing device (16) being a fastening element (18) for fastening on the robot arm and a contact element (36) with a contact surface (40) for contact with the plastic workpiece. For precise contact, it is provided that the contact element (36) is arranged so as to be movable in relation to the fastening element (18) in the direction of the plastic workpiece and is spring-biased.

Description

The present invention relates to a device for processing a plastic workpiece according to the preamble of claim 1.

In the case of plastic workpieces, their subsequent processing to the injection molding process (eg milling, punching, etc.) is widely known. For example, recesses must be introduced in dashboard covers for motor vehicles and weak cuts - for example, for an airbag cover - performed. In soft plastic surfaces (so-called skins) weakening cuts are often introduced with a knife.

In so-called hard plastic parts (eg polypropylene) it is known to produce cuts by means of milling devices with highly accurate gantry systems. However, such highly accurate portal systems are very expensive and relatively inflexible with respect to the component location and the inclusion of the component.

The use of so-called hot knives for debuffs in hard plastic materials is also problematic, as these methods tend to cause visibility and burrs in removing the knife from the workpiece. Machining by means of laser devices is usually expensive, there may be toxic fumes and there is a tendency to visibility of the introduced weakening cut in airbag covers.

The present invention is particularly concerned with the introduction of weakening cuts in large, hard plastic workpieces, in particular so-called I-panels, as used in particular in vehicles in cheaper price segments. Especially for simply exported vehicles in some local markets, such "hard plastic" elements for I-boards have prevailed. These plastic workpieces are made of, for example, a cheaper polypropylene material and typically have distortions, some of which may be of greater magnitude. These utilisations make it difficult to work with high-precision processing machines (gantry machines) because the component may not be in a position in which it is suspected.

The DE 101 33 279 C1 shows a machine tool for machining a plastic workpiece according to the preamble of claim 1, wherein during the machining, a grinder by spring-biased attachment to the machine tool allows a stroke compensation around a central position around. In this way, curvatures of the workpiece surface during a feed of the machine tool can be compensated by the movement stroke of the grinder.

The DE 10 2006 004 932 A1 shows a hold-down device for a machine tool, which allows the pressing of workpieces during processing and at the same time allows a relative movement between the machine tool and the workpiece both in the direction of the pressing force and in a plane perpendicular to the pressing force level around a central position.

An adjustment of the center position of the machine tool relative to the workpiece in both aforementioned machine tools, however, is possible only by an adjustment of the machine tool.

Object of the present invention is therefore to provide a device for processing a plastic workpiece, in particular of a hard plastic material, which may have faults and therefore difficult to machine with high-precision processing machines to specify, which are adjusted in a simple manner relative to the plastic workpiece to be processed can.

The above object is achieved by the features mentioned in claim 1.

Accordingly, in a device according to the invention a robotic device is provided, which is movable with a plurality of axes of movement. The robotic device has at least one robotic arm on which a processing device is provided. The processing device is fastened to the robot arm via a fastening element and has a contact element with a contact surface for engagement with the plastic workpiece to be processed. The fastening element can be moved by means of the movable robot device according to the programming of the robot device along a predetermined path over the corresponding clamped workpiece.

According to the invention, it is now provided that the abutment element is movably arranged with respect to the fastening element in the direction of the plastic workpiece and in the process - also in the direction of the plastic workpiece - is spring-biased.

With this procedure, the actual position of the component wall, which has, for example, a fault, secondary. Due to the movable arrangement and the spring preload faults are easily compensated when driving over, the spring preload presses the contact surface of the processing device with a certain force, which depends on the spring constant, against the plastic workpiece. This can be the Traversing movement for the robot device according to the per se given design data for the plastic workpiece can be programmed. The fault can move within the movement possibilities of the contact element.

Furthermore, the movement tolerance compensation allows the use of simple movement machine without special accuracy requirements. Moreover, the use of highly accurate product images in the use of the device according to the invention for achieving the desired accuracy in the resulting residual wall thickness is no longer necessary. Nevertheless, the use of surface-friendly materials (eg gumming) on the product intake is still possible.

Further, according to the invention, the contact element is adjustable in its thickness, so that a predetermined distance between the tip of the machining tool and the contact surface is variable. This distance corresponds to the immersion depth of the machining tool in the workpiece.

Preferably, the mobility between the fastening element and the contact element can be realized by means of a carriage, which preferably slides along the fastening element.

According to a further preferred embodiment of the invention, the processing device is provided in the form of a milling device, which has a milling spindle with a drive motor and a milling shaft, at the tip of a milling head is arranged. The milling shaft preferably extends through the contact element, wherein the milling head is spaced from the contact surface by a predetermined distance. This distance corresponds to the immersion depth of the milling device in the workpiece.

According to one embodiment of the invention, the predetermined distance is automatically changed during product processing.

Overall, this makes it possible to introduce a defined weakening cut into a workpiece (eg a hard plastic element), provided that the thickness of the hard plastic element corresponds to the given assumptions. However, this is usually the case.

The present invention will be explained in more detail below with reference to a concrete embodiment and with reference to the accompanying figures. The figures show in

1 a schematic perspective view of a processing device arranged on a robot device,

2 a detailed view 1 with the front part of a robot arm, on which the processing device is arranged,

3 another perspective schematic representation of the processing device according to the invention,

4 a schematic side view of the processing device according to the invention,

5 another perspective schematic representation of the processing device and

6 a final perspective schematic view of the processing device according to the invention in a direction from below.

The device described in the specific embodiment for processing a plastic workpiece comprises according to 1 a robot device 10 , which in the present case is a six-axis robotic device, by means of a base plate 12 attached to the ground.

At the front end of a robot arm is a front pivot 14 arranged on which a processing device 16 by means of a processing plate 18 is attached.

At the machining plate 18 is a sled 20 held back and forth (agility represented by the double arrow). The sled 20 can move within a given distance, which is determined by attacks.

Between the sled 20 and an upper support plate 24 is a spiral spring 22 interposed the sled 20 biased in the direction of the plastic workpiece, not shown (in the figures down). At the sled 20 is a holding plate 26 arranged, in turn, a housing 28 is attached. In this is a spindle machining device with a spindle housing 30 added. The spindle machining device has at its rear end (in the figures above) a spindle drive 32 on, the one emerging at the other end of the spindle device spindle shaft 34 rotatably driving. At the front tip of the spindle shaft is a milling head 38 provided, with a clamped plastic workpiece (not shown) can be edited.

The holding plate 26 has at its lower end a right-angled bending fastening tab 35 on, which has a central bore. In the figures below the fastening strap 35 is a spacer 36 arranged, which likewise has a bore which coincides with the bore of the fastening tab 35 coaxially aligned.

The peculiarity of the spacer 36 lies in the fact that it is made adjustable in its thickness (eg by loosening and twisting). At the bottom surface of the spacer 36 is a contact surface 40 provided, which is supported during machining of the workpiece against this.

The spindle shaft 34 protrudes through the two holes of the fastening tab 35 as well as the spacer 36 such that the milling head 38 over the spacer or its contact surface 40 survives. The supernatant defines the penetration depth of the milling head 38 in the plastic workpiece to be processed.

During operation of the device according to the invention is first on the adjustable spacer 36 the machining depth set with which the milling head 38 to penetrate into the workpiece. Subsequently, the robot device 10 with the processing device 16 guided along a predetermined, programmed path over a clamped and not shown here plastic workpiece. The robot arm presses the processing device 16 so against the workpiece, that the contact surface 40 attached to the workpiece with the force determined by the spring. This will apply the entire to the mounting plate 26 arranged device against the spring bias of the coil spring 22 pressed slightly backwards.

This bias is applied when moving the robotic device 10 maintained, with the retaining plate 26 can move when passing a rejection of the plastic workpiece in the direction of the double arrow and thus automatically adjusts. The maximum tolerance with regard to the rejection is determined from half the stroke that the slide can cover.

The advantage of the present invention is that the robot arm does not have to be guided over the workpiece with absolute accuracy, and unexpected distortions can be easily compensated for. Thus, it does not occur that the robot device either presses the machining device too tightly onto the workpiece during a corresponding fault or that the contact surface lifts off from the workpiece. Furthermore, especially caused by the motion machine leadership inaccuracies of the tool are compensated by the allowed movement tolerance compensation in the tool. In the presence of a defined wall thickness so accurate attenuation cuts can be introduced.

LIST OF REFERENCE NUMBERS

10

Robot device

12

Base plate of the robot arm

14

Front swivel joint

16

processing device

18

mounting plate

20

carriage

22

spiral spring

24

support plate

26

Retaining plate

28

casing

30

spindle housing

32

spindle drive

34

spindle shaft

35

mounting tab

36

Adjustable spacer

38

milling head

40

contact surface

Claims (4)

Device for processing a plastic workpiece, comprising a robot device that can be actuated preferably over a plurality of axes of movement ( 10 ), on whose robotic arm a processing device ( 16 ) is provided for processing the plastic workpiece, wherein the processing device ( 16 ) - a fastener ( 18 ) for attachment to the robot arm, and - a with respect to the fastener ( 18 ) in the direction of the plastic workpiece movably arranged and spring-biased contact element ( 36 ) with a contact surface ( 40 ) to bear on the plastic workpiece, characterized in that the contact element ( 36 ) is adjustable in its thickness, so that a predetermined distance between the tip of the machining tool and the contact surface ( 40 ) is changeable. Apparatus according to claim 1, characterized in that between the fastening element ( 18 ) and the contact element ( 36 ) a sleigh ( 20 ) is provided. Apparatus according to claim 1 or 2, characterized in that the machining tool as a milling head ( 36 ) and a holder ( 28 ) is provided, in which a milling spindle ( 30 ) is arranged, the milling shaft ( 34 ) the abutment element ( 36 ), wherein the at the milling shaft ( 34 ) arranged milling head ( 38 ) the predetermined distance from the contact surface ( 40 ) is spaced. Device according to one of the preceding claims, characterized in that the predetermined distance during the processing of the plastic workpiece is automatically changed.

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