DE1704864B2 - Method and device for the continuous production of endless, helically curved plastic tubes or casings - Google Patents

Description

The invention relates to a method for continuous borrowing Manufacture of endless, helically curved plastic hoses or dams through Pressing out a hot plastic mass from an annular slot mounted in a blow head by widening it of the still plastic tube by means of a dosed amount of air guided into the interior of the tube and Retention of this supplied amount of air in the hose by means of squeezing rollers, the hose is cooled differently over its circumference. Such round and helically curved intestines (like fie are also present in the carcass) are used in the meat and sausage industry. They are preferred in the production of certain types of sausage.

All attempts to make these coronary casings from synthetic materials, such as. B. polyamides, produced lu unsatisfactory results. Only skin fiber casings can so far be produced in the shape of a wreath. The production of such skin fiber casings is described , for example, in German patents 686891, 6 84 784 and 38 585.

A skin fiber mass that has been opened up by suitable pretreatment is replaced by a ring-shaped one Gap between a jacket pipe and a durin centric mounted rotating core in the tower of an endless, but straight tube pressed out. This If desired, the hose can be wound onto an endless mandrel in a helical manner. Sprayed to keep the intestine in this state with tannins like Wood smoke distillate or glyoxal, so tnu hardening chi. whereby the spiral shape (coronary intestine) is stabilized.

With the procedure outlined above, uiso is only a natural product (skin fiber mass) in egg; n coronary intestine convicted.

It is also already known to "straight hoses" by extruding thermoplastic masses from one Producing an annular gap using the so-called tubular film blow molding process (see e.g. plastics technology Dictionary by A. M. W i ι ι Γ υ h t, Vol. 2. Carl Hansen Verlag, Munich 1959).

A thermoplastic mass rode out of an annular gap, which in turn was in the so-called blow head is stored. The blow head consists of an inner core or mandrel, that of the blow head shell or blow head housing is surrounded.

The ring gap in the blow head is connected to a screw press, via which hot thermoplastic material, for example ^{polyamide at 225 C} C, is continuously pumped into the ring gap. In the interior of the blow head mandrel there is also a bore through which air can be supplied.

After leaving the annular gap, the still very hot mass that emerges is obtained in the form of a hose. This Hose is at a distance of about 1 to 2 m above the exit gap by a pair of nip rollers guided. At the same time, some air is blown through the hole in the blow head mandrel. This expands the the hose is still very hot and soft. Since the pair of squeeze rollers prevents the air from escaping in the This is part of the hose and prevents the blown air from escaping downwards Hose, which is located between the exit plane of the annular gap and the squeeze roller puar, constantly filled with air.

This air cushion has the task of the original, small diameter of the from the annular gap expanding the exiting hose to about three times. On the way between ßlaskopf and With a pair of pinch rollers, the hot hose naturally cools down.

The cooling is supported by a ring. at a distance of about 3 to 5 cm above the exit plane of the annular gap is arranged. The hose must pass through this ring. This On its inside, the ring again has a fully encircling slit through which everyone can air Sides is blown perpendicular to the outer surface of the inflating tube.

When a constant amount of thermoplastic is pressed out of the annular gap in the die head per unit of time and the withdrawal speed of the hose as well as the temperature and the amount of air that is above the Air ring exits, is also constant, then the hose is just above the air ring at its maximum Reach diameter. This remains - because the one enclosed between the blow head and nip rollers Air cannot escape - also constant.

If you want to increase the expansion, i.e. the final diameter of the plastic tube, then you have to do more Supply air through the hole in the blow head.

In this way, too, just become endless

Hoses manufactured. Most of the time you cut them open afterwards to get a foil. But one has Such plastic tubes are already filled with sausage mass. The manufacture of curved hoses »Using synthetic materials is not possible using the known method.

in the DT-AS 11 89 ^ S ¹ ! a method and a device are also described only for the production of straight hoses with unequal wall thicknesses over the circumference made of thermoplastic material. The problem with such hoses with unequal wall thickness, which are fed to a blow molding device for further deformation into a hollow body (e.g. in bottles), is that they bend on the way between the extruder and the blow molding device if they are not guided by guides at this bend hinders. The prevention of this undesirable curvature is the task of the DT-AS 1189 261. This is achieved in that the more strongly cooling areas of the circumference are warmed. DT-AS 12 08478 also relates to a method and a sirang press for producing a straight plastic pipe. The coolant is essential to the invention here. CB-PS 8 54 368 and US-PS 29 26 384 also relate only to the production of straight hoses by the blown film process. B. to generate irregularities in the hose in a controlled manner.

The object of the invention is therefore to produce a uniformly curved, endless plastic hose by extrusion.

This object is achieved according to the invention in that the expanding tube before it is reached of its final and largest diameter! symmetrically cooled and the curving one Hose is then guided in a semicircle up to the pinch point.

Such endless helically curved hoses can then be cut into shorter pieces, which can then be used as wreath intestines.

According to a preferred embodiment, the asymmetrical cooling is carried out by blowing on the from all cables Hose in a plane inclined to the axis of the hose.

Here the external cooling takes place in different Distances above the level of the thermoplastic Mass from the annular gap in the Itatt die. On the side where the cooling starts later, than on the opposite side, the hiasse remains plastic longer. Since at the same time the one from the The hose emerging from the annular gap in the blow head is constantly under tension (the rotating pinch rollers lent the hose out of the annular gap, so to speak), the softer side is consequently stretched more than the the opposite, the temperature of which is noticeably lower due to the earlier blowing. As a result of various Longitudinal expansion forms a helical tube.

The method according to the invention can be assisted by the fact that the mandrel in the die in known to be eccentric. In this case·; points the exiting hose to each other by 180 ° Points of different thicknesses immediately upon exit from the annular space.

The invention also relates to a device for carrying out the method according to the invention, consisting of an extruder with a screw and a blow head provided with an air supply, which has a concentric or eccentric annular slot, as well as squeezing rollers for squeezing the blown air and devices for different cooling of the hose in certain areas, which is characterized in that as the tube is arranged with cooling air downstream of the blowing head, a relative to the axis of the tube inclined nozzle ring for the mutual blowing.

In a preferred embodiment of the device, the nozzle ring consists of two in different, transverse to the axis of the hose extending planes and mutually offset by 180 " Half rings.

The invention is explained in more detail with reference to the drawings. The F i g. 1 shows schematically an embodiment of the device. In the extruder 1 Poly amide is heated to about 230 ⁰ C and fed to the blow head. 2 The polyamide emerges from the annular slot 3 in the form of a tube. The otherwise usual closed nozzle ring is now divided into two semicircular halves 4 and 5, which are mounted in different levels above the exit plane 3 ', 3 "of the polyamide compound from the ring slot. FIG. 2 shows a view of the half-ring 4, in which air enters via the supply line 6. This air exits from a slot located on the inside of the half-ring 4 and strikes the outer wall of the inflating plastic hose 7 - essentially perpendicularly.

The half ring 5 is constructed like the half ring 4. However, it is closer to the exit level 3 '. 3 "located and also offset from the half-ring 4 by 180 '.

Since the air from the half-ring 5 earlier on the (in Fig. 1) right side of the inflating plastic tube occurs as the air from the half-ring 4 on the left side of the plastic tube, so bends the latter to the right.

In the inflated state (the air required for inflation was pumped in via a supply line located in the blow head 2, but not shown), the intestine is fed to the squeezing rollers 9 ', 9 "via auxiliary rollers - (FIG . 1), which - as from Γ Fig. 3 can be seen - are conical in shape. After passing the squeeze point 9, the casing is flat and curved and can be wound onto a supply roll.

4 shows schematically in section and in top view an eccentric mounting of the mandrel in the die head. The plastic hose emerging in this embodiment has greater thicknesses on the left than on the right. If such a hose is shown in FIG. 1 curved, then the end product, i.e. the coronary casing, has approximately the same thickness everywhere because the initially thicker one Side was also stretched the most.

F i g. 5 shows schematically in section and in plan view the usual concentric positioning of the dome in the die. The emerging in this embodiment Plastic hose initially has the same - that is, immediately above the exit plane 3 ', 3 "of the annular gap 3 Thick on. If such a hose is shown in FIG. 1 curved, then the end product, i.e. the Coronary gut, on the side on which the greater stretching took place, thinner wall thickness than on the side, that wasn't stretched that much.

1 sheet of drawings

Claims (4)

Patent claims: 1. Process for the continuous production of endless, helically curved plastic hoses or intestines by pressing out a hot plastic mass from one in a blow head stored ring slot by widening the still plastic hose with a metered. in the inside of the hose guided amount of air and switching back this amount of air supplied in Hose by means of squeezing rollers, the hose being cooled differently over its circumference is characterized in that the expanding tube before reaching its final and largest diameter asymmetrically cooled and the curved hose up to the pinch point in a semicircle to be led. 2. The method according to claim 1, characterized in that the asymmetrical cooling takes place by blowing on the hose on all sides in a plane inclined to the axis of the hose. 3. Device for performing the method according to claims 1 and 2, consisting of an extruder with a screw and a blow head provided with an air supply, the one concentric or eccentric ring slot, as well as from Quelschwal / s for squeezing the Blown air and from devices for different cooling of the hose in individual areas, characterized in that behind the blow head an inclined relative to the axis of the hose Nozzle ring (4, 5) is arranged for blowing cooling air onto the hose on all sides. 4. Apparatus according to claim 3, characterized in that the nozzle ring consists of two half-rings (4, 5) arranged in different planes extending transversely to the axis of the hose and mutually offset by 180 ^r.