DE10335273B4 - Method and device for producing a multipart driving ring for a subcaliber projectile in fiber composite construction - Google Patents

Abstract

Method for producing a multipart driving ring for a subcaliber projectile in fiber composite construction,
in which
a) a winding element segmented into n elements is provided with an external thread, which predetermines the positive-locking zone to the projectile to be driven,
b) the segmented elements of the mandrel are widened by an intermediate expansion of an expansion body by a certain amount,
c) the winding mandrel is equipped with several layers of fabric over its length,
d) the fabric layers are impregnated with a synthetic resin,
e) the blowing ring blank is cured in a mold in an autoclave,
f) the hardened driving ring blank is shaped,
g) the sabot blank is disassembled along its elements with a separating tool, the separating cut width corresponding to the widening dimension,
h) the sabot blank undergoes a final outer shape determination.

Description

to Acceleration of sub-caliber balun ammunition in the barrel Supplementary body used, filling the volume between ammunition body and tube caliber. Of the The floor driving gas pressure can not escape to the outside. The supplementary bodies are under the name sabot or sabot known.

At which used to accelerate high performance subcaliber used sabots the requirement is made, the existing gas pressure as possible small total mass of the system sabot penetrator in kinetic energy convert and thus the penetrator as the actual payload one possible to accelerate high speed. The connection between sabot and Penetrator can be done in two ways, either form-fitting by means of thread, Grooves o. Ä. or non-positively by friction. The present invention primarily relates to the generally used positive connection. The inventive solution However, it is also frictionally engaged Connections valid.

To The essential functions of a driving ring thus include the transport of the Subcaliber bullet in the acceleration phase, ensuring the gas-tightness and the release of the projectile after completion Acceleration.

The latter requirement requires that after leaving the accelerator tube, the detachment of the sabot must be done by the penetrator. This is generally achieved in a constructive manner such that the drive ring does not consist of a single component, but rather of several segments which are practically identical to one another (for example, 3 parts each at 120 ^° , 4 parts at 90 ^° , etc.). For the safe transport of the projectile in the barrel, it is essential that despite the segmentation of the sabot in several individual components, the gas-tightness is maintained. This can be done by the introduction of additional sealing elements; Also possible and advantageous are constructive measures, such as form-locking elements in the contact surfaces (eg a cross-toothing).

High-strength aluminum alloys with a density between 2.7 and 2.9 g / cm ³ are generally used as standard materials for driving rings. It can now be assumed that modern materials and processing methods can also be used to advantage in driving ring construction.

To These newer materials include fiber composites. by virtue of their excellent relationship the mechanical properties (high rigidity and strength) based on the specific gravity are the fiber composites best for suitable for lightweight construction. In the field of sabot construction can by right and targeted use of these materials a significant reduction the dead weight can be achieved.

The DE 196 21 474 A1 shows a method for producing a multi-part drive ring for a sub-caliber projectile. The driving ring is made of light metal. The driving ring blank is already rotated in its undivided state to its final shape. Only then does the segmentation of the driving ring take place. The deviation from the circular shape in the cross section, which is present after assembly of the segments due to the joints, is accepted.

The DE 30 33 041 A1 relates to a method for producing a driving ring for a subcaliber bullet. As a material, a light metal or a fiber-reinforced plastic are suitable. The method provides that are milled with a slot cutter graduation joints in the drive ring. However, material bridges are retained. As a result, the integrity of the drive ring remains until it is properly disassembled during the launch.

From the DE 40 41 716 A1 is a method for producing a drive ring for a Unterkalibergeschoss in fiber composite construction known. In this case, individual wedges and plates are pressed with each predetermined orientation of the fiber layers to drive ring segments. From the resulting segments of the driving ring is composed later.

The EP 0 989 382 A2 relates to a method for producing a multi-part drive ring for a fiberglass sub-caliber projectile. Each segment of the drive ring is made up of individual wedges. Each wedge is previously made from several layers of prepregs.

The GB 1 384 196 A shows a winding mandrel with a cylindrical shell. A longitudinal slot in the cylindrical shell in conjunction with a widening device make it possible to change the outer diameter of the winding mandrel. This facilitates the production of tubular bodies made of fiber-reinforced plastic.

In the EP 0 176 688 B1 A method is described for efficiently producing a one-piece, conical and disk-shaped fiber reinforced plastic component (for use as a central spring valve spring retainer). To a conical mandrel several tissue layers, each with / without a circular cutout (depending on the diameter of the central bore), on a central, conical mandrel through "Impaling" fixed. The use of fabric layers with intersecting weft and warp threads are ideally suited for this application.

When using fabric layers without a bore, a single fabric layer [0 ⁰ | 90 ⁰ ] is axially fixed on a mandrel. The fibers (chain and weft), which were originally arranged at right angles to each other on the fabric layer, experience a local displacement through the mandrel. Here, these fiber bundles lay semicircular around the threaded rod. If one uses several, successively arranged fabric layers, it comes through the displacements in Gewindestabnähe to revaluations (accumulation of the displaced fiber bundles). This revaluation has little effect on the first layer of tissue, the fibers are virtually all in a plane perpendicular to the mandrel. Only by arranging many layers of tissue one behind the other, the angle of attack of the layers changes to the mandrel. If the fiber orientation of the fabric layers one behind the other is not identical, but arranged rotated against each other, a "homogeneous" winding of the mandrel is formed. If tissue layers with a bore are used, the diameter of the bore in the tissue layers determines whether revaluations (bore diameter <mandrel diameter) are produced or not (bore diameter ≥ mandrel diameter), ie the development of a setting angle. The angle of attack of the fabric layers can additionally be influenced by means of a mold which predetermines a certain angle of attack.

The Fibers run longitudinally the opening essentially in the circumferential direction and thus take the strain along the opening circumference on. At the outer edge By contrast, the fibers are approximately radial. By the uprisings and thus by the changing Angle of the tissue layers to the threaded rod and the angle of attack the first layer of tissue can be adjust the fiber flow to the force curve. An axial on the threaded rod attacking force causes in the circumferential direction around the mandrel lying fibers an extension, ie tensile load (load direction corresponds to the fiber direction). The Fibers are stressed there in an ideal way and direction.

To the load-oriented arrangement of the individual layers is the blank on the central mandrel either only axially or both axially and also compressed radially and then cured in an autoclave.

Unfortunately the known method is not suitable for the production of sabots. Should a sabot around a threaded rod, z. B. by winding or simple stacking from many individual fabric layers or a similar process from initially one single, contiguous Component produced, it is formed during the subsequent segmentation through the division (saw blade width) as well as through that To be introduced cross-toothing (cross-tooth height) a "material loss", which is a gas-tight assembly prevented the resulting items on the threaded rod. The gas-tight assembly of the sabot components on the threaded rod let yourself only again by a subsequent machining or reworking reach the internal thread.

Become the loads occurring in the system sabot-penetrator during the Considered acceleration phase, occur in the transformation of the applied gas pressure in kinetic energy at the interfaces between penetrator and drive ring locally very high shear stresses on. At the drive ring itself both normal stresses (pressure, tensile forces) as well as tangential stresses (shear stresses).

Of the the strongest claimed area is the interface between sabot and Penetrator, which designed in the design of the system must be that ensures a safe acceleration of the penetrator is.

attracts If one considers this load distribution, then - if the sabot is made in the way just described - straight the strongest claimed area, namely the thread, to be subjected to a machining finish. This reworking has serious disadvantages locally the properties of the fiber composite, because by machining processes on the working surfaces micro-damage arise in the system fiber matrix.

Of Further arise when screwing or skewering the many in a row arranged fiber single layers (process: stacking of fabric layers) Local loosening (synonymous with a disturbance in the orientation of the fibers in the immediate vicinity of the threaded rod). The resulting not ideal with fibers, but with one filled to high matrix proportion threads to lead Alone to a local deterioration of the mechanical Properties of the fiber composite. By reworking the thread become the loosened up and with too high a proportion of matrix material filled original threads removed, but by the cutting process arise more Disadvantages of microdamage in the fiber matrix composite.

The required post-processing prevents the application of the known from the outset Method, locally to achieve at the junction between sabot segment and penetrator favorable mechanical properties of the fiber composite (ideal fiber concentration, avoidance of local micro-damage) by its use at this point.

Of the in the independent ones claims 1 and 6 specified invention is the object of the previously in the sabot building used metallic materials, such as aluminum (in different alloys), substituted by fiber composites.

These The object is achieved by the Characteristics of the independent claims 1 and 6 solved. The specified solutions refer to a process for producing sabots Fiber composite building materials and an apparatus for carrying out the method.

The Advantages of the invention are that now an efficient Manufacturing process for a one-piece sabot (which is finally broken down into several parts) Fiber composite material with precisely defined and the force curve adapted fiber profile and a concentration of fibers in the internal threads to the disposal stands.

embodiments The invention will be described below with reference to the drawings. Here are each as a schematic diagram the

1 a subdivided into four thread segments F threaded mandrel A with inclusion for a cross wedge D or E;

2 a threaded mandrel A in the spread state by means of inflatable hose B;

3 the contour of the mold C;

4 a cross wedge D without gearing;

5 a mandrel A in the spread state, spread with a cross wedge D without teeth;

6 a cross wedge E with toothing;

7 a threaded mandrel A in the spread state, spread with a toothed cross wedge E.

• • Ausgangspunkt ist ein in n Elemente segmentierter Wickeldorn. Dieser wird mit einem Gewinde versehen, welches exakt der Formschlusszone Geschoss/Treibring entspricht. Anstelle eines Gewindes kann auch ein beliebiger anderer Formschluss verwendet werden. Diese Segmente des Gewindedorns A stellen die Negativform des herzustellenden Formschlusses dar.
• • Aufweitung des Gewindedorns A durch eine geeignete Vorrichtung, so dass die einzelnen Elemente einen bestimmten, kontrollierten Abstand voneinander aufweisen. Dies stellt den Kern zur Herstellung eines im wesentlichen zylindrischen und einteiligen Treibring-Rohlings zur Verfügung.
• • Fertigung eines im wesentlichen zylindrischen Treibring-Rohlings in einem Stück, wobei die Schnittstelle zur Nutzlast, also die als Formschluss und/oder Reibschluss ausgebildete Kraftübertragungszone in der endgültigen Form erzeugt wird, ohne dass in dieser Zone eine Nachbearbeitung erforderlich wird.
• • Erzeugung von Treibkäfig-Segmenten durch Teilung des Rohlings in n Elemente.
• • Kompensation des Materialverlusts, der durch die Teilung entsteht.
• • Kompensation des Materialverlusts, der durch eventuell erforderliche Bearbeitungen an den Trennfugen der Treibring-Elemente entsteht (z. B. zusätzliche Dichtungsmaßnahmen, Querverzahnung, etc.).

The production process for sabot has the following features:

• • The starting point is a mandrel segmented into n elements. This is provided with a thread which corresponds exactly to the positive locking zone projectile / driving ring. Instead of a thread, any other positive connection can be used. These segments of the threaded mandrel A represent the negative form of the positive connection to be produced.
• • expansion of the threaded mandrel A by a suitable device, so that the individual elements have a certain, controlled distance from each other. This provides the core for making a substantially cylindrical and one-piece drive ring blank.
• • Production of a substantially cylindrical driving ring blank in one piece, wherein the interface to the payload, so designed as positive locking and / or frictional force transmission zone is produced in the final form without reworking is required in this zone.
• • Generation of sabot segments by dividing the blank into n elements.
• • compensation for the loss of material caused by the division.
• • compensation for the loss of material resulting from any necessary machining operations on the parting lines of the driving ring elements (eg additional sealing measures, cross-toothing, etc.).

As already mentioned, a threaded rod should be used instead of a conical mandrel (see above) so that the "conical" bore becomes a "cylindrical" bore. For the burden of the driving ring element, this has no wesentli effect, since a thread as a series connection of several cone elements, now, however, with a larger "cone angle", be viewed can.

It several layers of fabric are stacked and in different angular orientations on the threaded mandrel A applied. These fabric layers can if necessary, have a bore. The size of the bore diameter controls the measure axial revaluation as well as the fitting of the fibers to the thread root.

Compared to the known methods (with conical mandrel) gives no change the resilience of the resulting molded body due to the previously described measures according to the invention and changes. Only by addressing the manufacturing process in the autoclave subsequent Division and thus by the not fully usable peripheral forces the maximum tolerable loads compared to the one-piece Blank then lower.

For the practical Using the method, three variants are given below.

Variant A of the method according to the invention:

in the Contrary to the known method, the individual fabric layers not impaled, but have to due to the existing thread "screwed" and thus fixed.

Of the Threaded mandrel A no longer consists of just one component. He is already in the initial state of several threaded individual segments F composed. The number of threaded segments F corresponds to the Number of segments of the driving ring to be manufactured. For practical Concerns the number of threaded segments F between 2 and 8. The following explanations refer to a driving ring with 4 segments.

The 1 shows the subdivided into 4 segments threaded mandrel A with a receptacle for a cross wedge D or E.

Of the Sabot blank is not made with the actual mandrel A as an inner mold - rather be the individual segments of the threaded mandrel A in the radial direction outward staggered, and precisely in such a way that the between the same size as the elements (in the circumferential direction) and so on are dimensioned that sufficient material for attaching a separating cut and - if so required - another is available to be machined forms. By the expansion receives the undivided blank thus does not have a circular symmetry close to the thread, but one (on the basis of the four-parting) approximating one another quadratically Cross-section.

To the separation of the blank into the individual segments and possibly required processing arises after assembling the Items inside again the exact cylindrical, with Threaded hole.

A radial expansion of the threaded mandrel A can be achieved by z. B. introduced into the composite mandrel A an axial bore becomes. In this hole can z. B. an elastic hose B inserted become. After the application of the individual fiber layers (as described above) is this hose B with z. As compressed air or a fluid under Expand pressure, so that the threaded parts of the mandrel F by the pressure radially outwards can move.

For clarity, the threaded mandrel A in the 2 shown in cross-section in a spread state. The radial expansion of the thread segments F is achieved by the introduction of an inflatable tube B in a corresponding bore of the threaded mandrel A.

The pre-impregnated Tissue monolayers that expand to a small extent radially, follow the displacement of the thread segments F. So serves the by the radial displacement of the threaded mandrel segments F resulting "gap" as a material addition, because he moves without any special further action both fibers and matrix material fills. This through Expansion created space compensates for the "loss of material", the later to be performed, cutting the segments needed is (a saw blade width is lost in the division, as well as the tooth height at the Cross-cut).

With In other words: An exact impression of the mandrel thread, only offset radially, remains even after the displacement of the threaded mandrel segments F obtained. The material in the division levels is for the resulting loss as a result of subsequent Separation and possible insertion of the cross-toothing sufficient.

One significant advantage of this method is that by the radial Displacement of the thread segments F both the fibers and the Matrix are pressed radially into the thread of the blank. Consequently creates an ideal image of the thread with an ideal fiber matrix concentration, because the local loosening caused by screwing or skewering of the composite is compensated in this way. This allows the mechanical properties of the "composite" driving ring segment penetrator, compared with the only screwed or impaled radial loosened, successively arranged individual layers, crucial be improved.

To curing the division takes place in sabot segments by z. B. sawing. Then let the sabot segments from the thread segments F of the threaded mandrel A separate. In one further work step is so much on all side segments Material machined removes that after the introduction of the axial Positive locking (eg cross-toothing) the sabot segments accurately assembled can be. The resulting "compound" thread of sabot segments is exactly the same as the thread of the unthreaded mandrel and thus coincide with that of the penetrator.

The Producing a cylindrical outer shape as the final shape of functional Sabotage must depending on the version the mold C by overwinding the outer contour respectively.

This disadvantage can be largely or completely compensated for by applying the shape which applies the radial pressure in the autoclave should be designed accordingly. First, the expansion of the threaded mandrel A must be taken into account by a corresponding Maßzugabe in the dimension of the mold C, so that the blank has a larger outer diameter than the caliber indicates. Furthermore, it is possible to proceed with respect to the geometry and thus the outer contour of the blank in two ways.

As the 3 shows, first, the internal geometry of the mold C is cylindrical. In this case, after the separation of the molded part in the segments reassembled driving ring must be machined on its now non-cylindrical outer contour on cylindricity and final dimension.

Should the cylindrical final shape of the sabot directly, so without special Post-processing can be achieved, is the internal geometry of the mold C to adapt accordingly, d. H. It arises, so to speak, by enlarging the outer contour of the threaded mandrel cross section. In this way succeeds in terms of the inner and outer shape the actual driving ring a close to final production.

To the curing in the autoclave is the first responsible for the radial pressure form away. Subsequently the axial sawing takes place of the component at the points where the material allowance is located. Now you have in this case four items with the threaded blanks. After separating the threaded blanks and the possible incorporation a cross-toothing or measures to guarantee The gas-tightness makes the four segments recovered ideal on a reference thread (same thread or penetrator) together.

Variant B of the method according to the invention:

The now presented method is similar to the first presented variant A, only with the difference that the radial expansion of the threaded mandrel segments F not with a hose B, but with a in 4 represented cruciform Aufweitwerkzeugs or cross wedge D is achieved. In this case, the front of the tool is wedge-shaped in order to better and easier to drive this into the threaded mandrel A can. As in 5 shown, the outer diameter of the expansion cross D is made slightly smaller than the core diameter of the threaded mandrel. Thus, during driving, it is prevented that fibers or fiber bundles of the individual layers are axially entrained or severed by the cross ends. As already described in variant A, the component is cured in an autoclave. The required finishing steps are also identical.

These Variant of the method according to the invention has opposite the variant described above the further advantage that by the cruciform Molding both a radial path and angle controlled expansion as well as a deflection-free expansion can be achieved. This allows a dimensionally accurate Manufacture and guarantee a high quality of thread forming.

Variant C of the method according to the invention:

at This method is composed of several threaded parts Blank before screwing in the tissue layers by single a corresponding tool widened in the radial direction or composed. The expansion-determining molding has the same outside dimensions as that Mandrel thread and has at the cross ends also a thread on, but with the difference that there the slope of the Thread is zero. Thus, it is possible to 'seamlessly' follow the threads, with alternating circle segments with normal slope and straight sections follow each other without a slope. In this way, the Then screw in tissue layers one after the other and slightly. When screwing the fiber monolayers follow the fibers of the threads of the Winding mandrel A, but are through the molding without thread pitch to the associated Thread passed, so exactly to that thread, the the fiber would be assigned without the presence of the wedge E.

For clarification is in 6 the cross-shaped wedge E with teeth on the web outer surfaces for mounting the threaded parts of the blank (on all sides same radial expansion) shown. The 7 shows the cross section of the threaded mandrel as a cross wedge with teeth in the spread state.

in the Contrary to the previously described methods, the threaded cross wedge E is to be regarded as a 'lost core' here he at the separation into the individual segments due to its dimensions inevitably destroyed must become.

As already mentioned, it is obvious that variant B of the process according to the invention The most appropriate method is to get one as efficiently as possible Produce divided drive ring blank.

A

mandrel

B

tube

C

mold

D

cross wedge without gearing

e

cross wedge with toothing

F

thread segments

Claims (7)

Method for producing a multipart driving ring for a Subcaliber bullet in Fiber composite construction, in which a) a segmented into n elements Mandrel with an external thread is provided, which dictates the positive-locking zone to the projectile to be driven, b) the segmented elements of the winding mandrel by intermediate joints of a Aufweitekörpers widened by a certain amount become, c) the mandrel over his length equipped with several layers of fabric becomes, d) the fabric layers are impregnated with a synthetic resin, e) the blowing ring blank is cured in a mold in an autoclave, f) the cured one Driving ring blank is formed, g) the sabot blank being disassembled along its elements with a separating tool, being the separating cut width corresponds to the widening dimension, h) the sabot blank a final one Outer shape determination experiences. Method according to claim 1, characterized in that the number of winding mandrel elements is between 2 and 8 pieces. Method according to claim 1 or 2, characterized that the expansion body as a cruciform solid accomplished is, the outer dimensions are smaller than the core diameter of the winding mandrel. Method according to claim 1 or 2, characterized that the expansion body a fluid filled, stretchable hose with changeable Internal pressure is. Method according to one of claims 1 to 4, characterized that the lateral surface the sabot mold in the same way as the winding mandrel in segmented form to respective Amounts widened is that when a separation of the drive ring blank by a cutting tool get lost. Apparatus for carrying out the method according to claim 1, characterized by a mandrel, the segmented elements by an intermediate amount of an expansion body by a selected amount can be pushed apart, and a surrounding negative mold. Device according to claim 6, characterized in that that the surrounding negative mold also has a segmented structure has individual elements, so that its lateral surface at certain Jobs by determinable sections is renewable.