DE202011002912U1 - Device for producing flat belts - Google Patents

Abstract

Device for producing flat belts from plasticizable plastic, comprising a first molding station with a first molding wheel (10) and a counter element interacting with the molding wheel (10), between which a first molding gap (11) can be formed, and one of the first molding station (I) Subsequent second molding station (II) with a second molding wheel (20) and a counter-element interacting with the second molding wheel (20), between which a second molding gap (21) can be formed, the first and second molding gap (11, 21) each one of is assigned to an extruder with plasticized nozzle (12, 22), characterized in that the first molding wheel (10) is used as a counter element of the second molding wheel (20) and the first molding wheel (10) of the first molding station (I) together with the second molding wheel (20) of the second molding station (II) forms the mold gap (21) thereof.

Description

The invention relates to a device for producing flat belts of plastifiable plastic, comprising a first forming station with a forming wheel and a counter-element cooperating with the forming wheel, between which a first mold gap can be formed, and a second mold station downstream of the first mold station with a second forming wheel and a with the second form wheel cooperating counter element, between which a second mold gap can be formed, wherein the first and second mold gap is assigned in each case one can be acted upon with plasticized nozzle.

Devices for the production of flat belts of plastifiable plastic are known, including, for example, on the DE 102 22 015 A1 is referenced. The known device comprises two successive forming stations, each having a forming wheel and a counter-element in the form of an endlessly circulating forming belt or a counter-roller, so that between the forming wheel and the counter-element, a mold gap is formed into which the plasticized plastic material used to produce the flat belt is introduced , For this purpose, one uses the help of extruders, which plasticize the plasticizable plastic material and bring under high pressure via a suitable tool as a melt in the mold gap.

Since in the known flat belt usually reinforcing materials, such. As cords made of steel, aramid, glass fiber or fabric are introduced, a partial belt is first prepared in the first forming station, which then partially supports the reinforcing material embedded on one of its surfaces and then further plasticized plastic material is formed on the partial belt in the second mold station to then form the finished flat belt, in the interior of which the reinforcing material is enclosed. Corresponding numbers of extruders are used for the provision of the plasticized plastic material according to the number of existing mold stations, which enormously increases the priming effort and makes the production of a homogeneous flat belt difficult, since both the rheology of the plasticized melt provided from the individual extruders and the mass flow rate of the used extruder must be exactly matched, which is associated with high costs and prone to failure.

From the DE 20 2009 003 295 U1 It is known to connect the first and second forming station with a common extruder and each provide metering between the extruder and the first and second forming station, whereby the process management during manufacture of the sub-belt and subsequent molding of the further plastic material to form the flat belt is simplified.

The known devices, however, has the disadvantage that the forming stations have a relatively large spatial distance from each other, so that first a first belt is made to the already further solidified state, the further plastic material is extruded to form the complete flat belt, so that a Extrusion seam is created, which creates a structural weak point of the flat belt. It is also known to provide a form wheel with web-shaped elevations for the exact positioning of einzulegender reinforcing fibers in the neutral zone, which define the position of the reinforcing fibers in the later flat belt. At the points where the reinforcing fibers rest on the elevations, often no polymer or elastomer layer can be built up so that winding noses form, where moisture can enter or dirt can accumulate. This is z. B. when using the flat belt in medical technology or the food industry necessarily to avoid.

In addition, designed in the known devices, the profiling of the flat belt, such as in the form of timing belt difficult. In particular, when a double-sided toothed belt is to be generated, as z. B. from the DE 20 2006 000 927 U1 is known, the creation of a constant synchronicity between the internal and external teeth of such a belt extremely difficult, regardless of whether the teeth on the inside and outside of the flat belt to be designed exactly congruent or with a constant desired phase shift.

An exact tooth synchrony can be achieved in the known devices only in that the teeth are machined out of an initially unprofiled flat belt, but this brings an additional operation and high material requirements with it, which is unsuitable for high volumes.

The object of the invention is therefore to propose a device of the type mentioned for the production of flat belts of plastifiable plastic, characterized by a particularly simple structure, high flexibility in terms of possible profiles of the flat belts produced, highest stability of the same and maximum tooth synchrony in the production of profiled Flat belt distinguishes.

To achieve the object, the embodiment of a device according to the features of the protection claim 1 is proposed according to the invention.

Advantageous embodiments and modifications of the invention are the subject of the dependent claims.

The proposal according to the invention is to use the first form wheel as a counter element of the second form wheel, d. H. the first and second forming wheels are immediately adjacent to each other and together form the mold gap of the second forming station. While accordingly the first forming wheel with a separate counter-element to form the first mold gap, for. B. a counter-roller or an endlessly circulating forming belt is designed, the second form comes without such a separate counter-element, since it uses the first form wheel as a counter element.

This results in a variety of advantages. First of all, the proposed solution according to the invention impresses with its particularly simple mechanical construction, since the number of parts required is enormously reduced compared to prior art designs.

Then, the spatial distance between the first forming station and in particular the first mold gap and the second mold gap of the second mold station is significantly reduced, since both are arranged along the circumference of the first forming wheel. This has the consequence that the partial belt created in the first mold gap after passing through the first mold gap is only partially cooled and transferred into a solidified state, so that the partial belt in not yet solidified, d. H. at least partially plastic state reaches the second mold gap, in which the remaining plasticizable plastic material from the second nozzle is added and connected when passing through the second mold gap with the previously created sub-belt to the final flat belt. In this way, the formation of a structure weakening extrusion seam is effectively avoided, so that the flat belt produced by the device according to the invention have an extraordinary stability. Also occur no more winding noses.

In addition, the use of the first form wheel as a counter element of the second form wheel allows the highly constant and synchronous training of internally and / or externally toothed flat belt, since particularly in the configuration of both form wheels with a desired tooth profile corresponding surface profiling the synchronicity of these surface profiles maintained during operation of the device constant is and to that extent the created flat belts are formed exactly synchronous tooth.

It can be provided to adjust the two form wheels to each other so that the inner and outer teeth are exactly congruent with respect to their teeth and tooth gaps or certain desired phase shift between the inner and outer teeth is set, which is then permanently maintained.

Advantageously, the forming wheels for this purpose have a common rotary drive and can also be formed with an adjustment for adjusting the phase shift between them.

Of course, in the context of the invention may also be provided, one or both form wheels smoothly, d. H. form without tooth profiling, which leads to the production of only one-sided toothed or completely untoothed flat belt. In the context of the invention, it is only necessary, depending on the desired teeth of the flat belt to be created to provide or exchange the corresponding form wheels, which can be made particularly simple.

A particularly compact embodiment of the device according to the invention is provided in that the inlet openings of the first mold gap and the second mold gap are arranged diametrically opposite to the first forming wheel.

According to one proposal of the invention, the nozzles of the first and second forming station can be acted upon by a common extruder with the interposition of melt pumps, so that melt of the same rheology is promoted to two mold gaps and insofar as a particularly homogeneous flat belt can be formed with low control effort. The mass control of the supplied melt at the first and second mold gap can be effected simply by influencing the speed of the melt pumps used.

According to an alternative proposal of the invention, however, it can also be provided that each nozzle can be acted upon by a separate extruder. Such an embodiment of the invention makes it possible in particular, flat belt with on the inside and outside different plastics, eg. B. Timing belt made of polyurethane with on the inner and outer surfaces of different hardness in a single device.

In a conventional manner, those produced in the device according to the invention Flat belts with reinforcing materials, eg. As cords made of steel, aramid, glass fiber or even a fabric. For this purpose, it is provided that between the first and second forming station, a corresponding feed device for the supply of the reinforcing material is provided.

The forming wheels of the device according to the invention can be temperature-controlled independently of one another according to a proposal of the invention. In this way, a precise influence can be taken on the cooling behavior of the plastic melt introduced into the first or second mold gap for forming the flat belt.

Furthermore, this embodiment allows a special temperature control along the first forming wheel, which ensures that the supplied from the feeder reinforcing materials sink only to a certain extent in the previously produced first sub-belt so that they later in the ideal case exactly in the neutral zone of Flat belt are arranged.

Further embodiments and details of the device according to the invention are explained below with reference to an embodiment illustrative drawing.

The single FIGURE shows a schematic side view of an apparatus for producing flat belts 4 , wherein the device comprises as essential components two forming stations, of which the first forming station is denoted by I and the downstream second forming station by II.

The first forming station I comprises a first forming wheel 10 , which in the illustrated embodiment with a superficial profiling to create a toothing of the later flat belt 4 on a first surface, e.g. B. the later outer surface is formed.

In terms of the circumference of the first form wheel 10 is at a position of about 12 o'clock a counter element in the form of a counter-roll 13 arranged so that between the counter roll 13 and the first form wheel 10 at about 12 o'clock the first mold gap 11 the forming station I is formed. This mold gap 11 is a nozzle 12 assigned, which is connected to an extrusion device, not shown, and from which melt of a suitable plasticizable plastic, for. B. a polyurethane in the mold gap 11 can be introduced.

About a non-illustrated drive device is the form wheel 10 in the illustration according to 1 rotated in the counterclockwise direction, so that after introduction of the melt in the mold gap 11 along the circumference of the first forming wheel 10 a melt strand is conveyed, which is a first part of the flat belt to be created 4 trains and at about 10 o'clock one more on the form wheel 10 expiring pinch roller 14 passes.

The first form wheel 10 is provided with a tempering device, so that a temperature of, for example, about 40-80 ° C can be effected, resulting in that the laid-up melt strand starting from the outer surface of the forming wheel 10 is cooled down radially outwards, ie the on the forming wheel 10 Immediately resting areas of the melt strand are cooled to the greatest extent and solidify before the radially outer regions of the melt strand on the first forming wheel 10 ,

In a position at about 7 o'clock on the first forming wheel 10 becomes reinforcing material in the form of cords 3 via a positioning roller 30 defined and supplied along the circumference of the first forming wheel 10 trained melt strand placed and then along the wider circumference of the forming wheel 10 carried.

Due to the already mentioned tempering possibility of the first form wheel 10 the cooling of the melt strand is adjusted so that the applied cords exactly in the later neutral phase of the flat belt 4 be positioned above and on the form wheel 10 solidifying melt strand are held in this position. In that regard, the cast in the first mold station I and depending on the profiling of the forming wheel 10 On one side profiled or smooth melt strand on a back thickness, which corresponds to the determination diameter of the subsequently applied tensile or reinforcing materials.

Then with the reinforcing material or the cords 3 provided and on the first form wheel 10 overlying melt strand at about 6 o'clock with respect to the first forming wheel 10 ie diametrically opposed 13 opposite arranged second forming station II fed from the first forming wheel 10 and the second form wheel 20 is formed. This is the mold gap 21 between the second form wheel 20 and the first form wheel 10 formed, ie in the region of the second forming station II, the first forming wheel is used 10 as a counter element to the second form wheel 20 ,

As in the first forming station I, a nozzle is also in the second forming station II, here the reference numeral 22 has, the second mold gap 21 assigned and via this nozzle 22 can from a non-illustrated extrusion device further plastic melt in the mold gap 21 be introduced, this together with the on the first form wheel 10 resting melt strand from the first mold station I passes.

When passing through the second mold gap 21 In this respect, further plastic material is applied to the previously produced melt, the applied reinforcing materials or cords 3 enclosed in the neutral zone and are intimately enclosed by the plastic melt.

Depending on the application, the second forming wheel smooth or, as shown in the embodiment with a surface profiling to form a toothing on the flat belt, here z. B. be formed along the inner surface.

In particular, when both the first form wheel 10 as well as the second form wheel 20 equipped with such a profiling to produce a toothing, which is on the created flat belt 4 produced toothing on the inner and outer surfaces permanently synchronously worked out, for which purpose it is provided in particular that the first and second forming wheel 10 . 20 synchronous to each other, z. B. via a common rotary drive, but with opposite direction of rotation.

After passing through the second mold gap 21 the melt is transferred from the first forming wheel to the periphery of the second forming wheel 20 pass, go through several more 23 and 24 characterized pinch rollers and then leaves the device as a finished and provided for example with internal and external toothed flat belt 4 ,

According to a proposal of the invention, the two nozzles 12 . 22 be acted upon by a common extruder with melt, including each nozzle 12 . 22 its own melt pump is assigned for throughput control. The use of a single melt source with a mass distribution on two melt pumps and merging of the melts in a flat belt 4 Ensures that always the same melt quality is combined with the same viscosity and thus a particularly intimate connection of the merging melts is achieved. This is also a prerequisite for the fact that the inserted reinforcing materials 3 be particularly intimately and evenly enclosed.

It is also possible to use any nozzle 12 . 22 to feed with its own extruder, which is particularly indicated when different melts from both nozzles 12 . 22 be discharged, z. B. a harder and a softer polyurethane.

It is understood that the second form wheel 20 may be provided with a suitable tempering device to control the cooling of the melt defined.

If both form wheels 10 . 20 unprofiled, ie formed with a smooth surface, is an untoothed smooth flat belt 4 generated while forming a forming wheel 10 respectively. 20 with a surface profiling a toothed belt with a toothing on the corresponding surface and the formation of both form wheels 10 . 20 With a surface profiling a flat belt with both internal and external teeth is produced. Due to the arrangement of the first form wheel 10 as a counter element to the second form wheel 20 Here, a constant synchronous formation of the teeth and tooth gaps on both the inner and outer surface of the flat belt 4 guaranteed in the simplest way.

Moreover, the form wheels 10 . 20 be provided with an adjusting device, which makes it possible, a predeterminable phase offset between the teeth generating projections and depressions on the first and second forming wheel 10 . 20 then permanently constant in the flat belt 4 is produced.

This synchronicity is not only due to the synchronous rotational movement of the two form wheels 10 . 20 but also that dimensional constraints due to shrinkage or strains on both profile sides of the flat belt 4 act the same and cancel each other out.

The flat belt produced on the device according to the invention with or without one / two-sided textured surface (s) appear to be made of one piece and have neither separation and joints or winding noses.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10222015 A1 [0002]
• DE 202009003295 U1 [0004]
• DE 202006000927 U1 [0006]

Claims (9)

Device for producing flat belts of plastifiable plastic, comprising a first forming station with a first forming wheel ( 10 ) and one with the form wheel ( 10 ) interacting counter element, between which a first mold gap ( 11 ) can be formed, and one of the first forming station (I) downstream second forming station (II) with a second forming wheel ( 20 ) and one with the second form wheel ( 20 ) interacting counter element, between which a second mold gap ( 21 ) is formed, wherein the first and second mold gap ( 11 . 21 ) each acted upon by an extruder with plasticized plastic nozzle ( 12 . 22 ), characterized in that the first forming wheel ( 10 ) as a counter element of the second form wheel ( 20 ) and the first forming wheel ( 10 ) of the first forming station (I) together with the second forming wheel ( 20 ) of the second forming station (II) the forming gap ( 21 ) forms the same. Apparatus according to claim 1, characterized in that the inlet openings of the first mold gap ( 11 ) and the second mold gap ( 21 diametrically opposite to the first forming wheel ( 10 ) are arranged. Device according to claim 1 or 2, characterized in that the nozzles ( 12 . 22 ) of the first and second forming station (I, II) can be acted upon by a common extruder with two intermediate melt pumps. Device according to claim 1 or 2, characterized in that each nozzle ( 12 . 22 ) can be acted upon by a separate extruder. Device according to one of claims 1 to 4, characterized in that between the first and second forming station (I, II) a supply device for the supply of reinforcing material is provided. Device according to one of claims 1 to 5, characterized in that the forming wheels ( 10 . 20 ) are independently tempered. Device according to one of claims 1 to 6, characterized in that the forming wheels ( 10 . 20 ) are smooth or formed with a tooth structure. Device according to one of claims 1 to 7, characterized in that the forming wheels ( 10 . 20 ) have a common rotary drive. Device according to one of claims 1 to 8, characterized in that the forming wheels ( 10 . 20 ) are formed with an adjusting device for adjusting a phase shift between them.

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