EP0018470B1 - Method for winding a tube and device for carrying out the method - Google Patents

Description

The invention relates to a method for winding a sleeve from a flat, essentially rectangular material blank, preferably made of cardboard on a winding mandrel, in which a clamp rotating with the mandrel holds the leading edge of the material blank and a fixed press bar holds the material blank during the winding presses against the surface of the mandrel.

In a method known from US-A-2 058 182, the leading end is inserted into a slot in the surface of the winding mandrel and held there by the rotating clamp. This has the decisive disadvantage that the front edge of the material blank is bent. When winding multi-layer cores, this kinked inner end is very annoying. On the other hand, with this method it is impossible to produce single-layer sleeves.

From DE-C-596 181 a winding machine is known which is provided with a clamp located on the outside of the mandrel surface which engages on the side edge of the cardboard blank. In addition, rollers lying next to this clamp are provided for pressing the blank onto the mandrel surface.

Such a machine is not suitable, in particular, for the rapid and efficient winding of single-layer tubes, since the blank is not held and guided exactly, and there is therefore a risk of lateral running.

The disadvantages mentioned could be avoided with devices for the pneumatic suction of the blank on the mandrel. However, such a method can only be used reliably with a limited material thickness of the blank and only above a certain minimum diameter of the dome.

The invention is based on the object of demonstrating a functional method and a device with which the disadvantages described are avoided and in particular there is no inward deformation of the leading blank edge.

This object is achieved according to the invention in that the clamp lying outside the mandrel circumference and rotating with the mandrel interacts with the mandrel surface in a clamping manner, and in that the fixed press beam is briefly lifted off the mandrel surface during passage of the clamp.

The clamp rotates with the mandrel and must therefore pass under the fixed press beam, which is pressed against the mandrel surface or the blank wound thereon, for example by spring force, in order to ensure the winding tension. This function includes the need for the press beam to act continuously on the cut. This is also the reason why, in the known devices, the clamp is arranged inside the mandrel circumference in order to be able to pass underneath the press beam without interference and so that the press beam can act on the blank immediately after the clamp. In contrast, in the method according to the invention, the action of the press beam on the cut immediately following the clamp is dispensed with. Rather, the press bar is raised briefly so that the clamp can pass under the press bar and then placed on the blank. However, this process takes place so quickly that the cut remains unaffected by the press beam only within a small area behind the clamp, the arc angle of this area (seen in cross-section) being so small that the subsequent tensioning action of the press beam is in this area can overcome effective circumferential friction.

This gives the advantage that the blank can also rest in the area of its leading edge without bending on the circumferential surface of the dome, and that the clamp can act a little behind the front edge of the blank, so that the front edge of the blank is exposed. As a result, an overlap seam of the blank can be produced without additional material loss.

The device according to the invention with a winding mandrel, which is provided with a clamp rotating with this winding mandrel, for forming a sleeve from a flat lying, essentially rectangular material blank, a fixed press beam being arranged, which device is known from US-A-2,058,182 , is characterized in that the clamp rotating with the mandrel is arranged on the outside thereof and pressed against the mandrel surface, and in that the fixed press beam can be lifted off the mandrel surface via a device connected to the mandrel during the passage of the clamp.

Different controls for raising the press beam are conceivable, for example with a special drive, the movement of which is controlled by a sensor which responds to the dome rotation. According to the invention, however, an embodiment is preferred in which a cam is provided on the mandrel that is connected to it in a rotationally fixed manner and serves to lift off the press beam.

As a result, the drive of the press beam for the lifting movement is immediately taken care of.

It is also very advantageous if, according to the invention, a plunger is attached to the press beam is brought, which is in operative connection with the cam.

Another feature of the invention is that the press beam and the clamp are arranged in their starting position on the outer circumference of the winding mandrel at a distance from one another which is sufficient for a sleeve overlap and into which a welding bar can penetrate for welding the sleeve seam. In this way, the clamp and the press beam are made usable for holding the overlap during the welding.

• Figuren 1 bis 4 in schematischer Axialdarstellung den Dorn und die zugehörigen Teile in unterschiedlichen Funktionsstadien.

The invention is explained in more detail below using an exemplary embodiment with reference to the drawing. Show:

• Figures 1 to 4 in a schematic axial representation of the mandrel and the associated parts in different functional stages.

The rotatably arranged mandrel 1 with the peripheral surface 2 is connected to a clamp 3 which can be pressed from the outside onto the peripheral surface 2 and rotates with the mandrel during the winding movement. The clamp can be lifted off to feed a new blank. Fixed and thus not rotating around the mandrel, a press beam 4 is provided, which is essentially guided radially to the mandrel 1 and, in the normal state, is pressed against the peripheral surface 2 of the dome 1 by spring force. To control the press beam 4, a cam which is connected to the mandrel 1 is provided, which acts with a cam elevation 10 on a plunger 6, which in turn is connected to the press beam 4.

• In der in Fig. 1 dargestellten Anfangslage ist die Klemme 3 von der Dornumfangsfläche abgehoben, so daß der Materialzuschnitt mit seinem vorlaufenden Rand zwischen Dorn und Klemme eingeschoben werden kann. Gemäß Fig. 2 wird er durch die Klemme 3 auf der Dornumfangsfläche festgeklemmt, und zwar in solcher Weise, daß sein vorderster Rand vor der Klemme frei liegt. Wenn sich bei der nachfolgenden Drehung der Materialzuschnitt mit der Klemme 3 dem Preßbalken 4 nähert, wird letzterer gemäß Fig. 3 angehoben, so daß die Klemme 3 darunter hindurchlaufen kann. Dies geschieht dadurch, daß die Nockenerhöhung 10 am Stößel 6 angreift und diesen sowie den damit verbundenen Preßbalken 4 gegen die Federkraft, die diesen sonst gegen die Dornumfangsfläche preßt, anhebt. Sobald die Klemme 3 unter dem Preßbalken 4 hindurchgelaufen ist, wird der Preßbalken wieder gesenkt, so daß er sich unter Federkraft auf die Oberfläche des zu wickelnden Zuschnittes auflegt und dessen Wickelspannung gewährleistet. Der Wickelendzustand gemäß Fig. 4 zeigt die Klemme 3 in der Ausgangsstellung. Das vorlaufende Ende des Zuschnittes hat sich unter das nachlaufende Ende geschoben, wodurch sich die Überlappung 8 zwischen der Klemme und dem Preßbalken bildet, die anschließend durch den Schweißbalken 9 geschlossen wird.

The device works in the following way:

• In the initial position shown in Fig. 1, the clamp 3 is lifted from the mandrel peripheral surface, so that the material blank can be inserted with its leading edge between the mandrel and the clamp. 2, it is clamped by the clamp 3 on the mandrel peripheral surface, in such a way that its front edge is exposed in front of the clamp. If, during the subsequent rotation, the material blank with the clamp 3 approaches the press beam 4, the latter is raised according to FIG. 3, so that the clamp 3 can run through it. This is done in that the cam elevation 10 engages the tappet 6 and lifts the tappet 6 and the associated pressure beam 4 against the spring force which otherwise presses it against the mandrel circumferential surface. As soon as the clamp 3 has passed under the press beam 4, the press beam is lowered again, so that it rests on the surface of the blank to be wound and ensures its winding tension. 4 shows the terminal 3 in the starting position. The leading end of the blank has slid under the trailing end, whereby the overlap 8 is formed between the clamp and the press beam, which is then closed by the welding beam 9.

Claims (5)

1. A method for winding a tube from a flat, essentially rectangular blank (7) made preferably of board on a winding mandrel (1), whereby a clamp (3) that rotates with the mandrel holds the front edge of the material blank in place and a fixed pressing strip (4) presses the blank against the surface (2) of the mandrel, wherein the clamp (3) located outside the mandrel (1) and rotating with the mandrel (1) has a clamping effect together with the surface (2) of the mandrel and wherein the fixed pressing strip (4) is raised briefly from the surface (2) of the mandrel when the clamp (3) travels by.

2. Device in particular for carrying out the method according to claim 1 with a winding mandrel (1) that has a clamp (3) which rotates with this winding mandrel as well as a fixed pressing strip (4) to form a tube from a flat, essentially rectangular blank (7), wherein the clamp (3) that rotates with the mandrel (1) is located outside the mandrel and is pressed against the surface (2) of the mandrel and wherein the fixed pressing strip (4) can be raised from the surface (2) of the mandrel when the clamp (3) passes by with the help of a mechanism connected to the mandrel.

3. Device according to claim 2, wherein a cam (5) is attached to and rotates with the mandrel (1) and serves to raise the pressing strip (4).

4. Device according to claim 3, wherein the pressing strip (4) has a lifting rod (6) attached to it which operates in combination with the cam (5).

5. Device according to one of claims 2 to 4, wherein the pressing strip (4) and the clamp (3) are located at such a distance from each other in their initial positions outside the winding mandrel (1) that there is enough space for one tube to overlap (8) and for a heat sealing strip (9) to seal the seam of the tube.

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