EP2906891B1 - Workpiece support - Google Patents

Description

The present invention relates to a workpiece carrier comprising at least two component elements, which are each composed of a carbon fiber reinforced carbon (CFC).

CFC workpiece carriers are used to support or hold workpieces in high temperature environments. For example, when curing or sintering of workpieces in industrial furnaces so-called charging racks are used as a carrier, wherein the heat treatment to be subjected to workpieces are placed on a support surface of the charging frame in the simplest case. Compared with workpiece carriers made of steel, workpiece carriers made of CFC are characterized in particular by increased temperature resistance and better dimensional stability.

The assembly of a workpiece carrier of a plurality of component elements is advantageous in terms of manufacturing costs and flexibility. In particular, this makes it possible to build complex frames, which are tuned to the respective workpiece type and quantity. The individual component elements can be plugged together, for example by means of frictional connection elements. A workpiece carrier for hardened material, which is composed of four frame-like assembled CFC strips is, for example, in DE 295 12 569 U1 disclosed.

In such workpiece carriers made of assembled CFC component elements, however, there is the problem that the respective frictional connection elements, such as guide ribs and grooves, manufactured with relatively high accuracy must be to prevent an undesirable loose connection on the one hand and jamming of the component elements during mating on the other hand. This is associated with a high production cost. Furthermore, due to the high temperatures and the strong temperature differences during a curing or sintering process, the frictional connection can be released and, as a consequence, undesired deformation of the entire workpiece carrier. In order to prevent such unwanted loosening of two connected component elements, they can be glued together, which in turn, however, is accompanied by an increased production effort.

In the DE 20 2010 015 436 U1 are interconnected CFC components assembled to a material carrier.

It is therefore an object of the present invention to further develop workpiece carriers of the aforementioned type with simple means in such a way that undesired release of the individual component elements is reliably prevented.

The object is achieved by a workpiece carrier with the features of claim 1.

According to the invention, at least two of the at least two CFC component elements are locked together. In such a latch engage at least two corresponding locking teeth form fit into each other and hold the two CFC component elements in a defined detent position, but under force overcoming the positive connection is possible in at least one direction. That is, when mating and possibly when pulling apart the component elements mentioned gear elements can slide past each other. In such a snap connection or click connection reaching the detent position is often audible and / or tactile perceptible ("clicking" or "snapping").

The two CFC components are therefore not only plugged together and thereby frictionally connected, but there is also a positive connection due to the latching, which increases the stability of the overall component and prevents unwanted loosening or loosening of the individual components. An elaborate gluing is not required here. Due to the increase in the load-bearing capacity of the connection caused by the positive connection, material can be saved in the design of the component elements, as a result of which the production costs decrease.

Fixed positive connections in the form of undercuts or pinnacles often require a complicated assembly of the component elements from different directions and in a precisely predetermined order. In contrast, a locking two component elements is particularly fast and easy. At a locking connection only comparatively low Maßhaltigkeitsanforderungen are also to make. Thus, it is possible, in particular, to offer kits for workpiece carriers, by means of which end customers can produce individual workpiece carriers as a function of the respective application by simply clicking in the individual parts.

The latching of the at least two CFC component elements can preferably be achieved by overcoming a latching resistor. The workpiece carrier can then be easily disassembled if necessary.

According to one embodiment of the invention, the force to be exerted on one of the two CFC component elements to overcome the detent resistance is at least 10 N. An adapted detent resistance on the one hand ensures sufficiently high security against unintentional release of the detent connection and on the other hand facilitates easy assembly and disassembly of the workpiece carrier , If a subsequent dismantling of the workpiece carrier is not considered, the detent resistance can also so be interpreted large that a non-destructive release of the locking is practically impossible.

According to one embodiment of the invention, the workpiece carrier can also comprise at least three CFC component elements, wherein each of the at least three CFC component elements is latched with at least one further of the at least three CFC component elements. This allows the construction of comparatively complex workpiece carrier, wherein the individual component elements are securely held together by the mutual locking. For example, a workpiece carrier may comprise two CFC component elements designed as longitudinal members, which are arranged parallel to one another and overlapped by at least one CFC component element designed as a cross member, the cross member being latched at each end to one of the longitudinal members. In this way, in particular the construction of a rust- or lattice-like workpiece carrier is possible, which is suitable for supporting a plurality of different workpieces.

In order to enable a simple and reliable holding of workpieces, a bearing surface for a workpiece can be formed on at least one of the at least two CFC component elements and preferably on each of the at least two CFC component elements. However, if required by the application, it is also possible for special fixing elements, such as recesses or stirrups, to be provided on the CFC component elements that overlap the workpiece to be held. Likewise, in certain applications, it may be advantageous to provide separate support or support elements, for example of ceramic, which are connected to the CFC component elements.

A locking projection may be provided on at least one of the at least two CFC component elements latched to each other, which latching projection is provided in a CFC component element locked to another of the at least two mutually latched components Locking engagement engages. The latching protrusion may be any area of material that protrudes from a base surface of the CFC component element, such as a flat wall. Depending on the application, such a locking projection may be tooth-shaped, hump-like or nose-shaped. Preferably, the latching projection is configured in the manner of a ramp in order to provide a ramp for easier latching. In principle, the latching projection could be designed as a separate component element. However, it is preferred if the latching projection is formed directly on the associated CFC component element.

It can be provided that the latching projection by a distance between 0.05 mm and 1.5 mm, preferably between 0.1 mm and 0.7 mm and particularly preferably between 0.2 mm and 0.4 mm relative to the base surface of associated CFC component element protrudes. Such distances have proved to be particularly favorable in that on the one hand a secure locking connection is ensured and on the other hand, a slight engagement or clicking one CFC component element in the other CFC component element is possible.

According to the invention, both a latching projection and a latching receptacle are provided on each of the at least two mutually latched CFC component elements, the latching projections and the latching receptacles of two mutually latched CFC component elements being mutually engaged. As a result, the construction of the workpiece carrier is simplified. In particular, care must be taken during assembly not that a sufficient number of CFC component elements with locking projection and on CFC component elements with locking receptacle is available, as always a catch receptacle is available for each locking projection. In this way, the construction of different workpiece carriers from a limited set of basic elements in terms of a modular system is possible.

Another aspect of the invention provides that the at least two CFC component elements can be plugged together for latching along an insertion direction, wherein the latching projection and the latching receptacle of each of the at least two CFC component elements are arranged one behind the other with respect to the insertion direction. When the CFC component elements are brought together along the insertion direction, the latching projection of one CFC component element thus automatically enters the latching receptacle of the other CFC component element and vice versa, so that a particularly simple latching is possible.

At least one of the at least two interlocked CFC component elements may have a groove for receiving a male portion of the respective other CFC component element, wherein the latching projection projects from a side wall of the groove. The male portion may be any portion of the respective CFC component member whose width is matched to the width of the groove. On the one hand, the groove then serves as a guide for the CFC component element to be inserted and on the other hand provides the locking projection serving for latching.

It can also protrude from two opposite side walls of the groove respective latching projections. As a result, the stability of the latching connection can be increased.

According to a specific embodiment of the invention, the at least two mutually locked CFC component elements are plate-like and each have at least one groove, wherein the grooves mutually engage. Such CFC component elements are relatively easy to produce and are particularly suitable for the construction of grid-like charging racks.

The groove may in particular have a rectangular cross-section. This allows a particularly simple production.

A further embodiment of the invention provides that at least one of the at least two interconnected CFC component elements, and preferably each of the at least two interconnected CFC component elements, has at least three spaced-apart grooves for receiving an insertion portion of another CFC component element. As a result, the flexibility in the construction of an application-related workpiece carrier can be further increased.

It can be provided that in at least one side wall of the groove two parallel and mutually spaced grooves are formed, between which extends the, in particular plateau- or hump-like, locking projection. Such a configuration of the latching projection has been found to be advantageous in terms of easy latching.

The grooves may have a rounded cross section, wherein the radius of curvature of the rounding is at least 0.1 mm and preferably at least 0.3 mm.

Furthermore, in at least one side wall of the groove may be formed a ramp-like locking projection and an adjacent thereto groove. The groove facilitates the snapping or clicking the locking projection into the associated locking receptacle.

Preferably, the at least two CFC component elements are each composed of a carbon fiber-reinforced carbon which comprises carbonized and / or graphitized polyacrylonitrile fibers. With such fibers particularly good results were achieved.

Furthermore, it is preferred that the at least two CFC component elements are each composed of a carbon reinforced with carbon fibers, carbon fibers and / or drawn fibers.

With regard to the fiber thickness, it is preferable that the at least two CFC component elements are each composed of a carbon fiber reinforced carbon comprising carbon fibers having an average diameter of between 5 μm and 10 μm. A particularly favorable value has been found to be an average diameter of the carbon fibers of about 7 μm.

With regard to the fiber content of the CFC component elements, it has proved to be advantageous that the at least two CFC component elements are each composed of a carbon fiber-reinforced carbon which is at least 30% by volume, preferably at least 50% by volume and more preferably at least 70 vol .-% of carbon fibers.

In order to ensure a secure use of the workpiece carrier during curing or sintering, it is preferred that the at least two CFC component elements have a temperature resistance of at least 1,500 ° C., and preferably of at least 2,500 ° C.

The workpiece carrier can be composed exclusively of, preferably identical, CFC component elements. This allows a particularly cost-effective production.

Preferably, the workpiece carrier has a size (BxLxH) of at least 50 mm × 50 mm × 10 mm, preferably of at least 100 mm × 100 mm × 10 mm and particularly preferably of at least 300 mm × 300 mm × 20 mm, for example of 1200 mm x 1,200 mm x 50 mm, on. Workpiece carrier of this Size are commonly used as charging racks when curing or sintering components.

Another object of the present invention is the use of a previously described workpiece carrier as a charging rack in a high temperature environment.

Fig. 1

ist eine Draufsicht auf ein CFC-Bauteilelement für einen Werkstückträger gemäß einer ersten Ausführungsform der Erfindung.

Fig. 2

ist eine vergrößerte Teilansicht des Werkstückträgers gemäß Fig. 1.

Fig. 3

ist eine Teilansicht eines CFC-Bauteilelements für einen Werkstückträger gemäß einer zweiten Ausführungsform der Erfindung.

Fig. 4

ist eine Teilansicht eines CFC-Bauteilelements für einen Werkstückträger gemäß einer dritten Ausführungsform der Erfindung.

In the following, the invention will be further described by way of these illustrative but nonlimiting examples with reference to the drawings.

Fig. 1

is a plan view of a CFC component element for a workpiece carrier according to a first embodiment of the invention.

Fig. 2

is an enlarged partial view of the workpiece carrier according to Fig. 1 ,

Fig. 3

is a partial view of a CFC component element for a workpiece carrier according to a second embodiment of the invention.

Fig. 4

is a partial view of a CFC component element for a workpiece carrier according to a third embodiment of the invention.

That in the Fig. 1 shown plate-shaped component member 11 is made entirely of a carbon fiber reinforced carbon (CFC) and is used to construct a workpiece carrier such as a Chargiergestells. The carbon fiber reinforced carbon comprises carbonized and / or graphitized polyacrylonitrile continuous filaments embedded in a matrix of carbon in a proportion of at least 80% by volume. Preferably, the fibers have an average diameter of about 7 microns.

As shown, the CFC component element 11 is configured in the form of an elongate strip and has a longitudinal axis L. Four grooves 13 of rectangular cross-section are formed along the longitudinal axis L spaced apart in the CFC component element 11. The width B of each groove corresponds to that in the Fig. 1 not apparent thickness of the plate-shaped CFC component element 11. Furthermore, the CFC component element 11 has four rectangular recesses 15, which are each adjacent to a groove 13 and whose width corresponds to the width B of the grooves 13.

As in particular from the enlarged view according to the Fig. 2 shows, each groove 13 has two opposing side walls 17, wherein in each of the side walls 17 are two mutually parallel and transverse to the longitudinal axis L spaced apart grooves 19 are formed. Between the two grooves 19 of a side wall 17 is in each case a slightly rounded Rastbuckel 20, which protrudes relative to the surface of the side wall 17 by about 0.35 mm.

Using the grooves 13, the recesses 15 and the Rastbuckel 20 can each two according to the Fig. 1 designed CFC component elements 11 are locked together, as will be explained in more detail below. In this case, the two CFC component elements 11 to be joined are initially arranged in a fundamentally known manner such that their longitudinal axes L run at right angles to one another and an upper-side groove 13 of one CFC component element 11 opposes a lower-side groove 13 of the other CFC component element 11. The two CFC component elements 11 are then brought together along an insertion direction E pointing transversely to the two longitudinal axes L, wherein the grooves 13 mutually intermesh. The seen in the direction of the longitudinal axis L laterally adjacent to the groove 13 portion of a CFC component element 11 forms a plug-in portion 21 which is guided by the groove 13 of the other CFC component member 11 and when plugging under elastic Deformation of Rastbuckels 20 slides past this. As soon as the recesses 15 have reached the latching bosses 20, the prestressing latching projections 20, which are under prestressing, snap into the recesses 15, as a result of which the two CFC component elements 11 are locked together. A release of the CFC component elements 11 from each other against the insertion direction E is only possible with an increased force while overcoming a latching resistor. Due to the shape and the size of the Rastbuckels 20 and by the choice of material, the locking resistance can be adjusted relatively accurately to an application-related default value. Using three or more CFC component elements 11 can be easily frame or lattice-like workpiece carrier in the manner described, in which the narrow sides 23 of the CFC component elements 11 form respective bearing surfaces 25 for workpieces. Such workpiece carriers are particularly suitable as charging racks in hardening or sintering furnaces. The fact that the associated component elements 11 are made exclusively of CFC, a sufficient temperature resistance and dimensional stability is guaranteed.

Assembling a workpiece carrier by latching the CFC component elements 11 is simple and requires no special knowledge. It can therefore also be performed by a respective end customer, while the manufacturer of the workpiece carrier provides only a set of CFC component elements 11 for individual mating as a kit. A particular advantage of the illustrated system is that there are no undercuts, which require the consideration of different plug-in directions and the maintenance of a particular order during assembly during assembly. There are also no gluing or separate fasteners such as pins or pins necessary because the stability of the CFC component assembly is ensured by the latches.

Fig. 3 shows an alternative embodiment of a CFC component element 11 according to the invention, wherein instead of a Rastbuckels here a locking lug 27 is provided with a ramp portion 29 and a shoulder 31. The approach shoulder 31 is followed by a single groove 19. The ramp portion 29 of the locking lug 27 forms a ramp for the insertion portion 21 of the other CFC component element 11, thus facilitating the mating of the two CFC component elements 11. The shoulder 31 provides for this in comparison to the embodiment according to the Fig. 1 and 2 increased locking resistance.

Another embodiment of the invention is in Fig. 4 shown. For engaging in the recess 15 is similar here as in the embodiment according to the Fig. 3 a detent 27 is provided, but no groove in the side wall 17 of the groove 13 is formed. The shoulder 31 runs here rather in a rounding 33. In the Fig. 4 is the distance A, by which the latching nose 27 protrudes from the side wall 17, highlighted by dashed lines.

Compared to a purely frictional nesting of the CFC component elements 11, the latch not only allows greater stability, but also a simplified assembly.

LIST OF REFERENCE NUMBERS

11

part feature

13

groove

15

Recess / locking receptacle

17

Side wall / base surface

19

groove

20

Rest hump / detent projection

21

insertion section

23

narrow side

25

bearing surface

27

Locking lug / locking projection

29

ramp section

31

neck shoulder

33

curve

L

longitudinal axis

B

width

e

insertion

A

distance

Claims (13)

1. Workpiece support comprising at least two components (11), which are each made of a carbon-fibre-reinforced carbon (CFC), at least two of the at least two CFC components (11) being latched to one another,
   characterised in that
   both a latching projection (20, 27) and a latching seat (15) are provided on each of the at least two latched CFC components (11), the latching projections (20, 27) and the latching seats (15) of two latched CFC components (11) mutually engaging in each case.
2. Workpiece support according to claim 1,
   characterised in that
   the locking of the at least two CFC components (11) can be released by overcoming a latching resistance.
3. Workpiece support according to either claim 1 or claim 2,
   characterised in that
   the workpiece support comprises at least three CFC components (11), each of the at least three CFC components (11) being latched to at least one other of the at least three CFC components (11).
4. Workpiece support according to at least one of the preceding claims,
   characterised in that
   the latching projection (27) is formed so as to be ramp-like.
5. Workpiece support according to at least one of the preceding claims,
   characterised in that
   the latching projection (20, 27) projects by a distance (A) of between 0.05 mm and 1.5 mm, preferably between 0.1 mm and 0.7 mm and particularly preferably between 0.2 mm and 0.4 mm, from the base surface (17) of the associated CFC component (11).
6. Workpiece support according to at least one of the preceding claims,
   characterised in that
   the at least two CFC components (11) for latching in an insertion direction (E) can be connected, the latching projection (20, 27) and the latching seat (15) of each of the at least two CFC components (11) being arranged one behind the other with respect to the insertion direction (E).
7. Workpiece support according to at least one of the preceding claims,
   characterised in that
   at least one of the at least two latched CFC components (11) has a slot (13) for receiving an insertion portion (21) of the relevant other CFC component (11), the latching projection (20, 27) protruding from the side wall (17) of the slot (13).
8. Workpiece support according to claim 7,
   characterised in that
   latching projections (20, 27) protrude respectively from two opposing side walls (17) of the slot (13).
9. Workpiece support according to either claim 7 or claim 8,
   characterised in that
   the at least two latched CFC components (11) are planar and each have at least one slot (13), the slots (13) mutually engaging.
10. Workpiece support according to at least one of claims 7 to 9,
    characterised in that
    at least one of the at least two latched CFC components (11) and preferably each of the at least two latched CFC components (11) has at least three spaced-apart slots (13) for receiving an insertion portion (21) of another CFC component (11).
11. Workpiece support according to at least one of claims 7 to 10,
    characterised in that
    two parallel and spaced-apart grooves (19) are formed in at least one side wall (17) of the slot (13), between which grooves the latching protrusion (20), which is in particular plateau-like or bulge-like, extends.
12. Workpiece support according to at least one of claims 7 to 11,
    characterised in that
    a ramp-like latching protrusion (27) and a groove (19) adjacent thereto are formed in at least one side wall (17) of the slot (13).
13. Use of a workpiece support according to any of the preceding claims as a charging rack in a high-temperature environment.

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