EP2431143B1 - Method and device for trimming an extruded product - Google Patents

Description

The invention relates to a method for cutting an extruded plastic tube by means of a separating device, and a device for cutting an extruded plastic tube by means of a separation device at least comprising: a rotatable about the extrusion axis of the tube basket with rocker and holder for a cutting tool, and arranged thereon a cutting blade, wherein the rotating basket is in the rest position in a defined starting position, wherein for cutting the cutting blade by means of the rocker is pivotable on the central axis of the tube.

In a pipe extrusion line, the produced pipes are usually cut by a pipe rotary saw to the desired length. There are two cutting methods: With a circular saw (this produces chips) or with a puncture knife (without cutting).

For cutting extruded tubes saws are usually used, with a circular saw blade is brought to the pipe to be sawn, immersed in the cross section of the tube and in the first step, the wall thickness severed. In the second step, the saw blade is passed around the pipe to completely cut the pipe. Here, the pipe to be cut is clamped during the sawing process; the saw carriage or saw carriage then moves synchronously with the continuous extrusion process with the extrusion speed ("flying saw").

If pipes are sawn, sawdust occurs. In addition, due to the friction of the saw blade on the pipe, in particular a plastic pipe, generates a static charge. This has the disadvantage that the sawdust sticks to the pipe, causing dirt. The resulting waste often has to be declared as hazardous waste, which makes recycling impossible.

With the latter, non-cutting separation, it is achieved to cleanly separate small pipe diameter with a thin cross-section, but it was not possible to successfully cut off even thick-walled pipes with large to very large diameter - about 2m diameter. In these pipes, the sawing described above was used again and again, which had the known disadvantages. One solution to the problem at the time was the utility model filed in 2001 DE 20 104 200 U1 achieved, it is proposed here that a knife carrier with means is telescopically adjustable and is guided by other means around the pipe to be cut down to cut the pipe. This solution then also large and thick-walled pipes could be cut without cutting.

• Schließen der Spannbacken - die Trommel fährt mit dem Rohr mit.
• Die Trommelrotiert um das Rohr.
• Die Schwinge wird eingeschwenkt und das Messer in die Rohrwand gedrückt. Durch die gleichzeitige Rotation der Trommel wird das Rohr abgeschnitten.

In a non-cutting saw, for example, in a drum which can rotate around the plastic tube, the saw unit is arranged. It consists of a rocker, which holds the puncturing knife, limit switches for the position of the puncturing knife and a drive for swinging the rocker. The steps for cutting a pipe are:

• Closing the jaws - the drum moves with the tube.
• The drum rotates around the pipe.
• The swingarm is swung in and the knife pressed into the tube wall. Due to the simultaneous rotation of the drum, the pipe is cut off.

Usually sits in the drum, a hydraulic pump which is driven by an electric motor. A swingarm with a puncture blade is powered by a hydraulic cylinder that comes from the store Hydraulic oil is fed, pivoted and brought over return springs back to the starting position.

The position of the rocker is monitored by limit switches. As the basket rotates, the signals of the limit switches and the current for the hydraulic drive must be fed through slip rings.

When setting up the saw for another pipe dimension, the new pipe diameter and the cutting depth on the rocker must be set manually.

The slip ring designs are complex and error-prone (soiling, oxidation, ...). The rotatable hydraulic unit is complex and there is a risk of leakage. In the event of a leak, the hydraulic oil sprays through the rotation in the saw unit and contaminates the unit. The manual setting of the pipe diameter and the pipe wall thickness during setup does not allow for automation.

The invention is therefore based on the object to provide a device and a method in which a separation of the tube without energy transfer takes place by means of slip rings.

To achieve the object, a method for cutting an extruded plastic tube by means of a separator at least comprising: a rotating around the extrusion axis of the extruded tube basket with rocker and holder for a cutting tool, and a cutting blade disposed thereon, wherein the rotating basket in the rest position in a is defined starting position and a battery is docked to a charging station, with a cutting pulse following steps in the order given triggers: decoupling the battery from the loading station, rotating the basket about the extrusion axis, pivoting the rocker in the direction of the central axis of the tube via a servo drive until the set immersion depth is reached, returning the rocker to the starting position, stopping the rotation of the basket, return the basket in the defined starting position, coupling the battery to the charging station, proposed. The charging station can be designed as a docking point, whereby the battery is charged directly or the battery is used in a docking point which is connected to a charging station to recharge the battery.

This makes it possible that the described problems can be avoided. All functions are remotely controllable via e.g. moving PLC and / or WLAN connection. For a simple conversion of the pipe diameter is possible.

The required energy and the control signals of the saw are not supplied in the operating state via slip rings, but the energy provided by a co-rotating battery and the battery is charged when the saw is in the rest state.

Further advantageous developments are given in the dependent claims. Where it is proposed to protect the cutting blade against breakage via a torque limiter of the servomotor or to measure the immersion depth via an incremental input and to finish the cutting process when reaching its maximum. Here, for example, radio signals can be used, which also moves the stopped basket via a limit switch in the rest position.

To solve the problem, a device is further proposed in connection with the preamble of claim. 8 characterized in that the pivoting of the rocker is done via a servo drive and the servo drive is powered by a battery with power.

In the rest position, the battery is via a docking point in a charging station where it can be loaded again until the next cutting process.

Fig. 1

eine Extrusionslinie und

Fig. 2

eine erfindungsgemäße Ablängvorrichtung für einen großen und

Fig. 3

für einen keinen Rohrduchmesser.

In the drawing, schematically, an example of the invention is shown, show

Fig. 1

an extrusion line and

Fig. 2

a cutting device according to the invention for a large and

Fig. 3

for a pipe diameter.

In the FIG. 1 shown extrusion line has an extruder 1. This extruder 1 is followed by an extrusion tool 2, in turn, a calibration station 3 and a deduction 4 are connected downstream. This is followed by a cutting device 5. Not shown is a subsequent storage device for the profile or a packing and stacking device.

The system components are connected via an electrical connection 7 to a system controller 6. All system parts are as shown here on a common extrusion axis 8. However, this is not absolutely necessary, since even deviating placements of the system parts lead to useful product results. The system controller 6 can be arranged as a separate unit in a control cabinet next to the extrusion line or integrated in the extruder 1. Intended interfaces such as LAN and / or CAN bus systems allow the controller to be integrated into a corporate network so that relevant data can be stored in a central computer and the input of the required parameters or specific terms can be entered via any network-integrated PC.

FIG. 2 shows a section of the cutting device 5 with a rotating basket 9, a rotatably mounted on the rotating basket 9 rocker 10, a holder for cutting tool 11 and the cutting tool 12 itself. Furthermore, a servo drive 13 and the battery 14 with the docking station 15, with the charging station is connected or even designed as a charging station to recognize. A servomotor 16 with rotary encoder, which is rotatably mounted on the rotating basket 9, is connected to a threaded spindle 17. The rocker 10 is in communication with the nut 18 which is mounted on the threaded spindle 17. When the servo motor 16 is actuated, the nut 18 is moved on the threaded spindle 17 and thus pivots the rocker 10 with the knife holder 11 and the knife 12 in the direction of the extrusion axis 8 or away. As a result, the knife 12 penetrates into the tube 19 and cuts it off without cutting.

The method and the device are suitable for different pipe diameters and can thus be used individually without changing components. FIG. 3 shows the use of a pipe 19 with small and FIG. 2 the use with a large diameter.

LIST OF REFERENCE NUMBERS

1

extruder

2

extrusion die

3

calibration Station

4

deduction

5

Cutting device

6

control

7

electrical connection

8th

extrusion axis

9

rotating basket

10

wing

11

Holder for 12

12

cutting tool

13

servo drive

14

battery pack

15

Docking point for 14

16

servomotor

17

screw

18

mother

19

Plastic pipe

Claims (9)

1. Process for the sizing of an extruded plastic tube (19) by means of a separator, comprising at least:

   a basket (9) rotating around the axis of extrusion (8) of the extruded tube (19) with a rocker arm (10) and bracket (11) for a cutting device, as well as a cutting device (12) fastened to it,

   with the rotating basket (9), when inoperative, remaining in a defined initial position and

   a battery (14) connected to a charging station,

   with a cutting impulse triggering the following steps in the given order:

   - Disconnecting the battery (14) from the charging station

   - Rotation of the basket (9) around the axis of extrusion (8)

   - Swinging in of the rocker arm (10) towards the center axis of the tube (19) by means of a servodrive (13) until the set immersion depth is reached

   - Resetting the rocker arm (10) to its initial position

   - Stopping the rotation of the basket (9)

   - Resetting the basket (9) into the defined initial position

   - Connecting the battery (14) to the charging station
2. Process according to claim 1, characterized in that the servodrive (13) is supplied with energy via the likewise rotating battery (14)
3. Process according to claim 1 or 2, characterized in that the exact position of the rocker arm (10) is controlled by a rotary incremental encoder.
4. Process according to claim 3, characterized in that the cutting device (12) is protected against breach by a torque limitation of the servodrive (13).
5. Process according to claim 3 or 4, characterized in that the immersion depth is measured by the rotary incremental encoder.
6. Process according to claim 5, characterized in that the cutting process is stopped when maximal immersion depth is reached.
7. Process according to one of the preceding claims, characterized in that the basket (9) is stopped by means of a radio signal.
8. Apparatus for the sizing of an extruded plastic tube by means of a separator, comprising at least:

   A basket (9), rotatable around the axis of extrusion (8) of the pipe (19), with a rocker arm (10) and a bracket (11) for a cutting device, as well as a cutting device (12) fastened to it,

   with the rotating basket (9), when inoperative, remaining in a defined initial position and

   with the cutting device swinging in to the centre axis (8) of the

   pipe (19) with the help of the rocker arm (10),
   characterized in that

   the swinging in of the rocker arm (10) is triggered by a servodrive (13) and

   the servodrive (13) is supplied with energy by a rechargeable battery (14).
9. Apparatus according to claim 8, characterized in that the battery (14), when in initial position, is connected to a docking station (15).

Images