DE4232158C2 - Method of manufacturing a sliding cylinder and sliding mandrel produced thereafter - Google Patents

Description

The invention relates to a method for producing a low-friction Surface of the sliding cylinder. It also affects one after the Process produced sliding mandrel, in particular as an intestinal mandrel for the Sausage manufacturing.

A shirred tube coated with tetrafluoroethylene for use in axial Gathering of synthetic tube sleeves in sausage production is known from DE 30 41 577 A1 known. The applicant also belongs to the internal state of the art Method for producing a low-friction lateral surface Sliding cylinder by pulling a cylindrical sliding tube onto a cylindrical one Core from another solid, in particular from metal, such as aluminum or Steel, or also made of plastic, the inner diameter of the guide tube just enough to insert the core loosely into the tube Amount is larger than the outer diameter of the core.

According to the aforementioned method, a sliding cylinder, in particular for Use as a roller or shirring mandrel. The shirthorn is said to if necessary, a free end to slide on and bellows Gathering and pressing together natural products intended for sausage production or have plastic casings or the like. The sliding tube should be out Polytetrafluoroethylene (PTFE) or from a similar low friction and anti-adhesive plastic, e.g. B. from a high temperature stable Polymid- Derivative. Under pressure, these can be briefly referred to below as Designated "sliding plastics"  Building materials flow so that under certain circumstances borders be provided for the direction of flow.

If you have a pipe, a roller, a shirring mandrel or the like surfaces with anti-adhesive and abrasion that are as low-friction as possible If you want to manufacture the outer surface, you can use a mentioned sliding plastic can be used with advantage. The However, this material is subject to greater mechanical tensile, buckling or shear forces not easily grown, so that one the sliding plastic only as a low-friction component a core of another solid material of the beginning ge named species. A match despite the low friction the sliding coating thus results in the case of strong frictional forces gradually wear, so that the Component because of the small thickness of the coating must be exchanged. For this reason, one has tried out the sliding plastic existing with massive pressed tem coat whose wall thickness is large compared to that of glide foil is to put on the respective core.

In previous practice, sliding tubes were removed from the cores neither shrunk, (axially) pressed on or glued on. When shrink-fitting, the guide tube is heated on the core postponed and then cooled. When it cools, it shrinks Guide tube in such a way that a very firm non-positive connection between the guide tube and the core. An essential one The disadvantage of this method is that the sliding tube shrinks after a short time and also in the Longitudinal direction is shortened. The prescribed jacket length  can not be set from the outset when manufacturing become. This is particularly disadvantageous if a roll surface with an exact axial length, or if an En de of the guide tube should hit a stop. The latter The case is important for the shirring mandrel mentioned at the beginning, one end of which is free, but the other end of which is egg NEN stop as an abutment when sliding open and together presses of the respective intestine. If on this End a gap by axially shrinking the sliding plastic arises between the abutment and the shrunk pipe the extremely compressed bellows from sausage intestine no longer be pushed off the shirthorn undamaged.

In order to avoid this disadvantage, one has ver looking for a sliding tube with an inner diameter that is small is smaller than the outside diameter of the core, below high pressure in the direction of the pipe axis on the core sen. This can also be a very firm non-positive Connection of guide tube and core are generated. Indeed the sliding tube is also used in the longitudinal direction compressed, so that because of the so-called memory this plastic after a short time with a relaxation expansion or longitudinal expansion of the guide tube is to be expected. Also in this way, rollers or shirring pins can be used Do not produce a defined axial sliding length from the start len. This applies especially to the shirring mandrels when the free En de des Raffdorns a (e.g. screwed into the core) cap pe, whose diameter is between the inside and outside diameter of the sliding tube is provided. If in this case  but the sliding tube remains for a long time after being pressed on stretches in the longitudinal direction - until it reaches its original length has reached - it can flow over the edge of the cap and thereby radially expand at the free end, such that a sausage bellows ring compressed on the mandrel intestine can no longer be removed from the shirthorn without being destroyed.

Finally, a substance has been tried in practice conclusive connection between a loose ge over a core pushed sliding tube and the core. This works however, is an otherwise preferred property of gliding art substance, namely the anti-adhesiveness, disadvantageously because it sufficient stability of the for many applications Connection between core and tube both in the axial direction as well as in the circumferential direction.

In order also for extreme applications, e.g. B. for rollers and External mandrels sufficient mechanical stability and from the front also a shape stabilizer corresponding to the needs a screw connection between Provide core and guide tube. To do this would have to be exactly in each other gripping threads on the outer surface of the core and on the Inner surface of the guide tube are made. Such positive connection would also be extreme apart from ge know a good torsional stress generated when screwing Shape stability can guarantee from the outset, the Her position is however too complex, especially for every diameter So separate tools must be provided and larger ones  Diameters are not standardized.

The invention has for its object a connection of Sheep tube and core along with manufacturing processes fen that is nearly as firm and dimensionally stable as the Screw connection, but with much less effort pose is.

The solution according to the invention exists for the above Process for producing a low-friction surface having sliding cylinder with a cylindrical core and a cylindrical jacket designed as a sliding tube, wherein the inner diameter of the sliding tube around one to insert of the core in the tube just sufficient amount greater than the outside diameter of the core is that the sliding tube by manufacturing or after-treatment in one for the user of the sliding cylinder provided temperature range ther mix and mechanically until permanent dimensional stability is stretched that the inner surface of the guide tube and given otherwise the outer surface of the core is roughly in the cylinder order be grooved that at least one of the ge corrugated surfaces with a shear harder than the guide tube Tending putty is coated and that the tube and the core before put together when the putty hardens.

An essential feature of the present invention is in being able to connect the slide tube before connecting with the core, e.g. B. already during production or at least by post-treatment, so relaxed that in the long run - in  provided temperature range - remains dimensionally stable. The Sliding tube should therefore be pretreated or post-treated so that it to a certain extent no longer has a "need" to shape itself change. Such a relaxed guide tube is to be invented according to the invention also during or through the connection with or mechanically not under due to the application on the core Tension. Such mechanical stresses would even occur - circumferentially - if that Sliding tube with a thread for making one form-fitting connection would be screwed onto the core.

According to the invention, it is preferred if both the inner surface surface of the guide tube as well as the outer surface of the core become. However, at this point due to the creasing under among other things, the anti-adhesiveness of the sliding tube in effect to be dubbed, it is also within the scope of the Erfin dung, the creasing only on the low-friction sliding tube inner surface and not on the outer surface of the core watch if this outer surface is enough ad anyway is adhesive.

The creasing according to the invention can be helical or helical be made in the shape of a kidney, but also from a single circle shaped grooves (continuous or broken) or the like consist. In practice, screw lines are the simplest to manufacture. The creasing on the inner surface and against overlying outer surface does not need the same or in to be matched. Groove depths of about 0.5 mm (at Cylinder diameters from 1 to 20 cm) are preferred.  

As the inner diameter of the guide tube - as assumed - larger than the outside diameter of the core the opposing surfaces do not anyway directly. According to the invention, between these two surfaces inserted a putty that is supposed to be stronger than the Guide tube material. The shear strength of the hardened Kitts should preferably be between the shear strength of Steel and that of the sliding plastic, in particular PTFE lie. Of course, the putty should also thermally Requirements of the respective application on the same measure as the sliding tube are sufficient.

While with the sliding cylinder cited at the beginning with Glue together smooth surfaces of core and slide pipe a sufficiently stable connection cannot be established was because the lanyard was not tight enough to the measure material of the guide tube could adhere, - by the resp Fabric bond produced against adhesive, that is, for stabilization act the connection was insufficient, - is according to the invention the stability of the connection essentially through Form-fit is justified because the hardening putty is not just egg cylinder with smooth inner and outer surfaces between Represents core and guide tube, but also in the grooves provided according to the invention. The limit of The stability of the connection according to the invention is therefore largely independent of the adhesive force between putty and Guide tube and practically only dependent on the shear stability of putty. Nevertheless, a material bond also carries with it  Adhesive behavior of the putty for stability. If that according to the putty, as required by the invention, after hardening shear strength than the sliding material results in a too same material and form-fitting connection with the advantages a pure screw connection, but without its disadvantages, So without the high manufacturing costs and without a Ver drilling tension from screwing on.

The solution according to the invention is for the sliding cylinder initially mentioned type, which consists of a sliding tube and a cylindrical core, with the two parts loose in are to push each other in that the sliding tube in one intended temperature range up to per relaxed form stability is that the zuge each other turned inner and possibly outer surfaces of the guide tube or core are grooved approximately in the circumferential direction and that between the inner and outer surfaces are more resistant to shear than that Sliding material of the guide tube hardened putty is provided.

A preferred embodiment of this sliding cylinder is a roller with low-friction surface and mechanically sta core, which can be used to advantage wherever it on low adhesivities, low friction and low Abrasion arrives.

According to another invention, the sliding cylinder, which after the Process is to produce, as shirring mandrel with a free En de to slide on and bellows-like gathering and -presses of natural and intended for sausage production  Artificial casings or the like used. On such Raffdorn, the z. B. can have a length of 1.5 m, can For example, a 150 m long one for making sausages hen intestine in its longitudinal direction accordion or fal Slip on tenbalgartig and then to a ring of for example, press together 15 cm of axial length. There with the high compression of the intestinal material with great force is pressed against the periphery of the shirring mandrel it takes considerable force to pull the ring off the shirring pin. Such forces can be applied and controlled. The meaning of the invention arises here Connection from the fact that the highly compressed annular The intestinal packet is to be moved relative to the sheath of the shirthorn, without moving the coat and without damaging the package dig.

Because the highly compressed intestinal package with great force against the Periphery of the guide tube is pressed, arise from Ab pull the package from the mandrel considerable friction forces that despite one assuming low friction of the sliding tube cause some abrasion, of limited life, too of the shirring mandrel according to the invention. Try ha ben show, however, that the service life compared to shirthorns of the previous type is about tripled. Improvements and white tere embodiments of the invention are in the dependent claims Chen specified.

Using the schematic drawing of an embodiment details of the invention are described. Show it:

Fig. 1 shows a longitudinal section through a shirring mandrel;

Fig. 2 is an enlargement of the connection between the sliding tube and the core of the shirring mandrel of FIG. 1.

The shirring mandrel shown schematically in Fig. 1 consists of a sliding cylinder, generally designated 1 , with a free end 2 , the closed end 3 of which is a flange 4 , e.g. B. with screw holes 5 has. The sliding cylinder 1 be consists of a core 6 , which can be hollow or solid, and a sliding tube 7 , which should consist of a low-friction and anti-adhesive material of the type mentioned.

Between the core 6, which is preferably in the form of a steel tube, and the sliding tube 7 , an overall connection 8 , which results in a positive connection, is provided. To produce this connection 8 are in the embodiment in the outer surface 9 of the core and in the inner surface 10 of the sliding tube 7 approximately in the circumferential direction with respect to the Zylin derachse 11 extending grooves 12 and 13 of the type described above, which do not engage, but one Allow core 6 and sliding tube 7 to be pushed over each other.

The space between the outer surface 9 and the Innenflä surface 10 of the connection 8 is filled according to the invention with a cement 14 , which after hardening has a shear strength that is greater than that of the material of the sliding tube 7th Since the putty 14 after hardening the parts summarized by the connection 8 holds together cohesively and positively, especially with irregularity and inequality of the grooves, relative movements between the core and the guide tube can only take place axially or in the circumferential direction if the putty were sheared off. Because of the high shear strength according to the invention of the hardened putty, there is thus a stability of the connection according to the invention which is not inferior to that of the applied sliding tube itself.

The putty to be provided according to the invention in connection 8 can be of very different types. It is selected so that it also meets the respective requirements for temperature resistance. One or two component materials can be used. Also suitable are materials that expand during hardening, e.g. B. in the manner of polyurethane foam. The person skilled in the art can find out the cheapest putty or glue, which under certain circumstances should also be acid-resistant.

Referring to Fig. 1, a slide cylinder 1 will be explained as a (substantial) part of a shirring mandrel. Such a shirring mandrel can have a cap 16 on the mandrel tip 15 , the diameter of which lies between the inside and outside diameter of the sliding tube 7 , so that the cap (for example screwed to a pin 17 with the core 6 ) cap 16 a flow of the sliding material in the direction of the cylinder axis 11 to the outside closes.

In a very similar manner, as shown in Fig. 1, a roller of the type according to the invention can also be produced. Such a roller can essentially look like the sliding cylinder 1 , but it has pins on the two longitudinal ends, which can be equipped with flanges in the manner of the cap 16 in order to prevent the material of the sliding tube 7 from flowing outwards.

When using the shirring mandrel according to FIG. 1 as such, a casing 19 intended for sausage production is applied in the direction of the arrow 19 to the mandrel and is "gathered" there with an alternating increasing and decreasing diameter. The application and gathering is done in the usual way. The approximately 1.5 m long sliding cylinder 1 is gradually pulled all over with the bellows-like shirred casing 18 . The next step is to compress the intestine 18 into an approximately 15 cm thick ring-shaped package 20 . This intestinal tract 20 is finally pushed off by means of a meshing between the flange 4 and Ga package 20 bel 21 in the direction of arrow 22 from the sliding cylinder. 1

A sliding cylinder, e.g. B. as a roller or shirring mandrel can by pulling a sliding tube onto a core from one on their solids keep their shape and do not deform produce the tension on the guide tube when fiction according to at least the inner surface of the loose on the core inserted sliding tube with an approximately in the circumferential direction of the Pipe axis extending grooving is provided and if the Space between the core outer surface and inner tube surface  filled with a putty, which after hardening is stronger than the material of the guide tube.

Claims (11)

1. A method for producing a low-friction lateral surface have the sliding cylinder ( 1 ) by pulling a cylindrical sliding tube ( 7 ) onto a cylindrical core ( 6 ) made of another solid, such as aluminum or steel, or also made of plastic, the inner diameter of the sliding tube ( 7 ) by an amount just sufficient for loose insertion of the core ( 6 ) into the tube ( 7 ) is greater than the outer diameter of the core, the sliding tube ( 7 ) being manufactured or after-treated in a for the application of the sliding cylinder ( 1 ) the intended temperature range is relaxed thermally and mechanically until permanent dimensional stability, the inner surface of the guide tube ( 7 ) is grooved approximately in the cylinder circumferential direction, at least one of the grooved surfaces is coated with a shear-resistant cement ( 14 ) hardening than the guide tube and the guide tube ( 7 ) and the core ( 6 ) are put together before the cement is hardened. 2. The method according to claim 1, characterized in that the outer surface of the core ( 6 ) is grooved approximately in the cylinder circumferential direction. 3. Sliding cylinder, in particular for use as a roller, consisting of a cylindrical friction tube ( 7 ) with a low-friction lateral surface and a cylindrical core ( 6 ) anchored in the sliding tube ( 7 ) made of another solid material, such as aluminum or steel, or also made of plastic, the inner diameter of the guide tube ( 7 ) being larger by an amount sufficient to loosely insert the core into the guide tube than the outer diameter of the core, the guide tube ( 7 ) in a temperature range provided for the application up to perma Nenten dimensional stability is relaxed, the inner surface of the guide tube ( 7 ) is grooved approximately in the circumferential direction and between the inner and outer surfaces of the guide tube ( 7 ) or core ( 6 ) a shear resistant than the guide tube ( 7 ) hardened putty is provided. 4. sliding tube according to claim 3, characterized in that the mutually facing inner and outer surfaces of the sliding tube ( 7 ) or core ( 6 ) are grooved approximately in the circumferential direction. 5. sliding cylinder according to claim 3 or 4, characterized in that when training as a shirring mandrel with a free end ( 2 ) for sliding and bellows-like gathering and pressing of intended for sausage manufacturing natural or plastic casings ( 18 ) or the like at the free end of Sliding cylinder ( 1 ) is anchored to a cap ( 16 ), the diameter of which lies between the inside and outside diameter of the sliding tube ( 7 ). 6. sliding cylinder according to one of claims 3 to 5, characterized in net that a helical or helical groove is provided. 7. sliding cylinder according to one of claims 3 to 6, characterized in net that at least some of the surfaces are irregular and / or different which is grooved. 8. sliding cylinder according to at least one of claims 3 to 7, characterized ge indicates that the surfaces are grooved about 0.5 mm deep. 9. sliding cylinder according to at least one of claims 3 to 8, characterized ge indicates that two-component putty is provided. 10. sliding cylinder according to at least one of claims 3 to 9, characterized ge indicates that a slightly expanding putty during curing is provided in the manner of polyurethane foam. 11. Sliding cylinder according to at least one of claims 3 to 10, characterized in that the core ( 6 ) is designed as a tube.