EP0085770B1 - Apparatus for cutting openings in pipes - Google Patents

Abstract

An apparatus for cutting openings in pipes of cuttable material, in particular in plastics drainage pipes has at least one cutter head carrying at least one cutter, the cutter head rolling at least in part on the periphery of the pipe and being positively driven for this by means of a planetary gear. By virtue of this, the cutting edge of the cutter moves around the pipe in an epitrochoid. The cutter head is provided with ridges engaging in transverse corrugations in the outer wall of the pipe. In order to be also able to cut openings in pipes formed at least in part with annular corrugations over their periphery, at least the cutter head is provided with helically extending ridges and the at least one cutter is disposed parallel to these ridges.

Description

The invention relates to a device according to the preamble of claim 1.

Such a device known from DE-C-22 30 767 has proven itself extremely well in practice since it enables continuous cutting of openings in corrugated tubes, specifically openings in the respective trough, with the course of the cutting edge of the respective knife on an epitrochoid the chip cut out of the outer wall of the tube is cut outwards, i.e. does not fall into the tube. The known device is, however, in terms of its application for special shapes of pipes, such as. B. annular corrugated tubes, which may additionally have a foot not provided with openings, in need of improvement.

A comparable device is known from DE-A-2810165, which has a cutter head which is provided with helically extending webs.

Proceeding from this, the object of the invention is to improve the generic device in such a way that even corrugated tubes can be provided with openings in the respective trough, both a defined insertion of the slots and a removal of the cut chips being achieved with reliable transportation of the tube should.

This object is achieved by the characterizing features of claim 1. The inventive design ensures that the tube is at least transported in its longitudinal direction by the cutter head, although the transverse shafts are each designed as circular rings or partial circular rings. With circularly corrugated or even partially circularly corrugated tubes with a foot, the chips cut out from the respective cutter head or cutter heads can be completely cut off by means of the scraping head, if necessary, which at the same time also contributes to the transportation of the tube. These measures increase the service life of the knives considerably, up to ten times their normal service life.

If - what happens relatively often especially with drainage pipes - the pipes are provided with a foot, i.e. with a non-circular section, then the measures according to claim 2 ensure that, on the one hand, proper transport takes place despite the frictional forces acting in the sliding bed and that on the other hand, no openings are cut in the foot area.

The measures according to claim 3 ensure that, on the one hand, the slippage between the scraping head and the tube occurs when the scraping head is being rolled, but on the other hand that the advancing effect of the scraping head is identical to the advancing effect of the knife head (s) and, if applicable, of the transport head (s).

• Figur 1 in Vorderansicht eine Vorrichtung nach der Erfindung entsprechend der Schnittlinie I-l in Fig. 2,
• Figur 2 einen Querschnitt durch die Vorrichtung entsprechend der Schnittlinie 11-11 in Fig. 1,
• Figur 3 eine Teil-Vorderansicht einer zweiten Ausführungsform der Erfindung entsprechend einem Sichtpfeil 111 in Fig. 4,
• Figur 4 einen Teil-Querschnitt durch die Vorrichtung entsprechend der Schnittlinie IV-IV in Fig. 3,
• Figur 5 eine schematische Darstellung der Abwälzbewegung des Messerkopfes am Rohr,
• Figur 6 eine schematische Darstellung der Abwälzbewegung des Schabkopfes am Rohr,
• Figuren 7 bis 9 das Entfernen eines nicht vollständig abgeschnittenen Spanes mit einem Schabkopf in unterschiedlichen Drehstellungen und
• Figur 10 einen Querschnitt durch Fig. 9 entsprechend der Schnittlinie X-X.

Further advantages and features of the invention result from the following description of exemplary embodiments of the invention. based on the drawing. It shows

• 1 shows a front view of a device according to the invention along the section line II in Fig. 2,
• FIG. 2 shows a cross section through the device according to section line 11-11 in FIG. 1,
• FIG. 3 shows a partial front view of a second embodiment of the invention in accordance with a viewing arrow 111 in FIG. 4,
• FIG. 4 shows a partial cross section through the device according to section line IV-IV in FIG. 3,
• FIG. 5 shows a schematic illustration of the rolling motion of the cutter head on the tube,
• FIG. 6 shows a schematic illustration of the rolling movement of the scraping head on the tube,
• Figures 7 to 9 the removal of a not completely cut chip with a scraping head in different rotational positions and
• Figure 10 shows a cross section through Fig. 9 along the section line XX.

In the device shown in FIGS. 1 and 2, a stationary, i.e. H. non-rotating housing 1 is provided which has a hollow hub 2 to which a protective cage 3 is fastened by means of screws 4. The pot-shaped protective cage 3 is closed on its side facing away from the hollow hub 2 by means of a cover 5 which is screwed onto the protective cage 3 with screws 6. The cover 5 has an inlet opening 8 concentrically with the central longitudinal axis 7 of the housing 1 for a pipe 9 to be explained further below.

By means of the screws 4, a fixed external ring gear, which is the sun gear 10 of a planetary gear, is connected to the housing 1. A hollow shaft 12 is rotatably mounted in the housing 1 by means of a ball bearing 11, onto which a drive flange 13 is screwed in a rotationally fixed manner by means of a thread 14. The inner diameter of the hollow shaft 12 arranged concentrically to the axis 7 is in any case significantly larger than the outer diameter of the tube 9 fed through the hollow shaft 12.

In the basket-like drive flange 13, pairs of planet gears 15, 16 and 17, 18 are rotatably mounted. The planet gears 15, 16 are arranged concentrically to one another and rigidly connected to one another, ie they are connected in a rotationally fixed manner to a common shaft, the planet gear 15 engaging in the sun gear 10. The two planet gears 17, 18 are also arranged coaxially to one another and rigidly connected to one another, ie they are also non-rotatable connected to a common shaft. The planet gear 16 engages in the planet gear 17 so that the planet gear 18 is also driven. The planet gear 18 engages in a drive gear 19, which in turn is rotatably mounted on a shaft 20 which is rotatably mounted in a bearing 21 in the drive flange 13. At the other end of the shaft 20, ie on the other side of the bearing 21, a three-part cutter head 22 is fastened to the shaft 20 by means of a threaded nut 23. In the drive flange 13 further pairs of planet gears 15, 16 and 17, 18 are rotatably mounted, which serve to drive a scraping head 24 or to drive transport heads 25. The scraping head 24 and the transport heads 25 are fastened in the same way as the cutter head 22 and approximately in a plane common to this and perpendicular to the axis 7 by means of threaded nuts 23 on shafts 20 which are mounted in bearings 21 in the drive flange 13 and which have a drive gear wheel 19 wear that engages in the associated planet gear 18. The sun gear 10 and the planet gears 15 to 18 and the drive gears 19 are designed in a manner known for planetary gears in such a way that with a full rotation of the drive flange 13 according to the direction of rotation arrow 26 the shafts 20 and thus the cutter head 22, the scraping head 24 and the transport heads 25 make exactly one turn around their own axis 27.

The tube 9 is a so-called circular corrugated tube with a foot 28, i. H. The tube 9, which has a circular cross section over the greater part of its circumference, has partially annular wave peaks 29 or wave troughs 30 lying in planes perpendicular to the axis 7. The cutter head 22 and equally the scraping head 24 and the transport heads 25 are each provided with a helical profile whose webs 31, 32, 33 engage in the troughs 30. In the present case, the cutter head 22, the scraping head 24 and the transport heads 25 are provided with webs 31, 32, 33 in the manner of a two-start thread, the pitch t of which therefore extends in each case over the axial extent of two webs 31, 32, 33. The pitch t of the cutter head 22, the scraping head 24 and the transport heads 25 is identical and the same as the axial distance between the next but one wave crests 29 of the tube 9. That the cutter head 22, the scraping head 24 and the transport heads 25 change every full revolution of the drive flange 13 once around its own axis 27 in the direction of rotation 34 relative to the drive flange 13, the tube 9 is pushed forward by the amount of the pitch t, that is to say twice the distance between two adjacent wave crests 29 in the transport direction 35, for each revolution of the drive flange 13.

Arranged in the hollow shaft 12 is a slide bed 36 which is adapted to the shape of the base 28 of the tube 9 and which penetrates the inlet opening 8 in the cover 5 and is fastened thereto by means of a screw connection 37.

So that the cutter head 22, scraping head 24 and transport heads 25 do not collide with the sliding bed 36 on their circulation around the tube 9, an area is cut away from each head 22, 24, 25, which otherwise has a circular cross section, the boundary line 38 of which at least corresponds to the development that would arise when the respective head 22, 24, 25 rolled past the sliding bed 36. Of course, an even larger part can be cut away, for example with a straight boundary line.

Since at least four heads 22, 24, 25 provided with a positive drive are provided in the exemplary embodiment according to FIGS. 1 and 2, two or three of them are always in engagement with the tube 9, so that despite the friction of the foot 28 of the tube 9 in the sliding bed 36 a proper feed of the tube 9 is guaranteed.

The cutter head 22 is constructed in three parts. It has a central knife carrier 39, on which knives 40 are attached, which have cutting edges 41 leading in the direction of rotation 34, which protrude beyond the webs 31. In the axial direction on both sides of this central knife carrier 39, pure web sections 42, 43 are formed. The knife carrier 39 and the two web sections 42, 43 and the knives 40 are clamped together by means of clamping screws 43a.

The knife 40 and the basic structure of the knife head 22 is known from DE-PS2230767. By means of the knives 40, water inlet openings 44 are cut into the tube 9 in a manner known in principle, in each case in the region of the wave troughs 30. Since the web 31 of the cutter head 22 is constructed in the manner of a two-start thread, that is also the knife carrier 39 extends over two courses, corresponding to the division t, the knives 40 - as can be seen in FIG. 2 - can be arranged so that the openings 44 in two adjacent troughs 30 are not arranged on an axis-parallel line, but offset against one another are arranged.

So that the webs 31, 32, 33 of the rotatable heads 22, 24, 25, which are in engagement with the tube 9, bear against the tube 9 with a slight prestress, the sliding bed 36 can be adjusted transversely to its longitudinal direction. For this purpose, 45 elongated holes 46 are provided in a flange through which the screw connection 38 passes.

The embodiment according to FIGS. 3 and 4 differs from that according to FIGS. 1 and 2 essentially in that two cutter heads 22 'are provided which are diametrically opposite one another. The storage and the drive correspond to that according to FIGS. 1 and 2. The arrangement of two cutter heads 22 'is possible because a normal circular corrugated tube 9' is provided with openings 44; so it is not a foot on tube 9 '. For this reason, no sliding bed is provided. A scraping head 24 is provided, which likewise has no recess. Since no slide bed is provided, it is also not necessary to provide transport heads which bring about an axial advance of the tube 9 '. In order to absorb the displacement forces, only at least one support roller 47 needs to be provided, which is not driven but is freely rotatably mounted in the drive flange 13 '. The cutter heads 22 'have four threads, that is to say they have four webs 31'. With one revolution of each cutter head 22 ', the tube 9' is thus pushed forward in the transport direction 35 by the axial distance of four webs 31 'in accordance with the division t'. Both cutter heads 22 'are of identical design, that is to say they can be interchanged. Since the knives 40 are not offset in the embodiment according to FIG. 4 compared to the embodiment according to FIG. 2, the knives 40 must therefore be mounted parallel to one another in the cutter heads 22 'at a distance of t' / 2. The upper cutter head 22 'cuts the openings 44 in the second and fourth wave troughs 30', while the lower cutter head 22 ', which is offset in the axial direction by t' / 4, cuts the openings 44 in the first and third wave troughs 30 ' . By rotating a knife head 22 'by half the knife spacing, the offset arrangement of the openings 44' results from the first to the second wave trough 30 'and from the third to the fourth wave trough 30'. This configuration and arrangement of the cutter heads 22 'enables the pipe 9' to be transported at twice the speed of the exemplary embodiment according to FIGS. 1 and 2, which is particularly suitable for pipes 9 'with a smaller diameter.

The principle of operation of the cutter heads which is known in principle is explained with reference to FIG. 5. a tube 9 'with a circular cross section being provided with openings for the sake of simplicity. Otherwise, the same reference numerals are used as in FIGS. 1 to 4, insofar as they are applicable here. 5, the cutting edge 41 of a knife 40 of a knife head 22 'or 22 moves on an epitrochoid E due to the described movement processes. The epitrochoid E is the curve which - as shown in FIG. 5 - from one point Namely, the cutting edge 41 of the knife 40 is described when a rolling circle k with a radius r rolls without slip on a leading circle K with a leading circle radius R and the distance A of the point (cutting edge 41) from the center point M of the rolling circle is greater than that Radius r of this pitch circle k. During the rolling motion, the center m of the rolling circle k moves on a circular line L. As shown in FIG. 5, the epitrochoid E forms a loop which is immersed in the conducting circle K. In the technical implementation, the rolling circle k is formed by the cutter head 22 'or 22, while the guide circuit K is formed by the tube 9' or 9. Each time the cutting edge 41 is immersed in the guide circuit K, i. H. in the tube 9 'or 9, an opening is cut into the tube 9' or 9, the knife cutting out a piece of the wall of the tube 9 'or 9 each time it passes through the small loop, so that the Cutting direction at the end of the cut is directed radially outwards, which is why the cut chip falls outwards.

The structure and function of the scraping heads 24 and 24 'result from FIGS. 6 to 10. The circular corrugated tube 9' has a radius Ra of the wave trough 30 ', while for the assigned radius Rb of the scraping head 24' (or 24) applies Rb = 2 x Ra. Since the scraper head 24 or 24 'is intended to make a full rotation about its axis 27 or 27' when the drive flange 13 or 13 'rotates relative to it, the scraper head has a slip of 50% on its circumference with respect to the trough 30 'of the tube 9', since the roll angle α in the tube 9 'on the one hand and in the scraping head 24' or 24 are the same. If the scraping head 24 'or 24 has moved by a scraping length a in accordance with the roll angle a with respect to the tube 9', then the circumference of the scraping head has moved further by the useful length b, where b = 2 x a.

As can be seen from FIGS. 7 to 9, cutting teeth 48.1, 48.2, 48.3 ... are provided on the circumference of the scraping head 24 or 24 ', the outer radius of which is equal to Rb. As can be seen from FIG. 7, when cutting an opening 44 - for example because the cutting edge 41 of a knife 40 becomes blunt - the chip 49 to be cut out has not been completely cut off. As can be seen from FIG. 7, a cutting tooth 48.1 has already passed the chip 49, the next cutting tooth 48.2 runs in the direction of the chip 49. As can be seen from FIG. 8, the subsequent cutting tooth 48.2 catches up with the chip 49 and cuts it off, as can be seen from FIG. 9. The chip falls into the protective cage 3, where it is drawn off together with the other chips through a lower extraction opening 50. To facilitate this removal, a guide plate 51 is fastened to the drive flange 13, by means of which the cut chips 49 are pushed to the extraction opening 50.

As can be seen from FIG. 10, the openings 44 widen towards the inside of the pipe 9 or 9 'by an angle β, which is particularly advantageous for drainage purposes. The reason for this is that the openings 44 are cut open essentially by cutting out one chip 49 from the inside outwards. As a result, the tube is slightly curved outwards in the region of a wave trough 30 or 30 ', as a result of which the plastic material of the tube is given a slightly conical, outwardly narrowing or inwardly widening cutting surface with the cutting angle β.

The tubes 9 and 9 'are made of plastic in upstream corrugated tube molding machines of a known type.

It should be added that the axes 27 and 27 'of the cutter head or 22 or 22' and the scraping head 24 or 24 'and the Tran sports heads 25 are shown in the drawing only for the sake of simplifying the drawing parallel to the axis 7 of the tube 9 or 9 '. In fact, they must be set in relation to the axis 7 in accordance with the pitch angle of the bars 31 or 31 ', 32, 33 resulting from the division t. This is achieved in that the last planet gear 18 and the associated drive gear 19 are designed as bevel gears with corresponding bevel angles. However, this measure is known and is also necessarily used in practice in the devices known from DE-PS 22 30 767.

Claims (3)

1. Apparatus for cutting openings (44) in pipes (9) of cuttable material, in particular in plastics drainage pipes, having at least one cutter head (22) carrying at least one cutter (40), the cutter head (22) rolling at least in part on the periphery of the pipe (9) and being positively driven for this by means of a planetary gear, so that the cutting edge of the cutter (40) moves around the pipe (9) in an epitrochoid, and the cutter head being provided with ridges (31) engaging in transverse corrugations in the outer wall of the pipe (9), and the apparatus having at least one support roller taking up thrust forces and resting against the pipe (9), characterised in that, for cutting the openings (44) in pipes (9, 9') which are at least in part annularly corrugated over their periphery, at least the cutter head (22, 22') is provided with helically extending ridges (31, 31') and that at least one cutter (40) is disposed parallel to these ridges, with a shaving head (24, 24') being provided, which is likewise provided with helically extending ridges (32) engaging in the transverse corrugations, and which is positively driven by the planetary gear with slippage with respect to the pipe (9, 9').

2. Apparatus for cutting openings in pipes (9, 9') having a foot which is not to be provided with openings, the foot being guided in a slide bed, according to claim 1, characterised in that at least one support roller is formed as a transport head (25) which is positively driven by the planetary gear and has helically extending ridges (33) corresponding to the transverse corrugations of the pipe (9) and engaging in these, and that cutter head (22) and transport head (25) are provided with cutaway regions, the boundary line (38) of each of which corresponds at least to the curve generated by rolling of the head (22, 25) on the pipe (9), no cutter (40) being provided on the cutter head (22) along this boundary line (38).

3. Apparatus according to claim 1, characterised in that the shaving head (24, 24') is drivable at the same speed of revolution as the at least one cutter head (22, 22') but has a diameter (Rb) greater by an integral number compared with the cutter head.

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