The invention relates to a method for producing friction linings by pressing a pourable mass (or bulk material, respectively), wherein the mass is pre-compressed against at least one carrier plate, and subsequently the pre-compressed mass is conveyed to a press and there is subjected to a final compression in a press mold having at least one cavity, as well as to an arrangement for producing friction linings by pressing a pourable mass, including a device for pre-compression, or preforming, respectively, of the mass against at least one carrier plate, and a press with a press mold having at least one cavity for final compression of the mass, the press following the pre-compression device via a conveying unit.
Various methods and arrangements, respectively, for producing friction and brake linings are already known.
On the one hand, complex hot pressing methods (so-called true positive mold methods) are known, e.g. from JP 10202678 A, in which a pourable mass is pressed in a heated mold under controlled pressure and temperature. In such hot pressing methods, pressing of the pourable mass is effected in a comparably complicated heated press device. Such production methods and arrangements require complex tools and machines and, accordingly, are cost-intensive.
On the other hand, less complex production methods with non-heated press forms are known. However, since for a plurality of friction lining masses very high press molds of a height of approximately 250 mm would be required for introducing the pourable mass into the cavity of the press mold, and such high press molds are not economical and also involve technical disadvantages, it is known to initially pre-compress the pourable friction lining mass in an additional method step. The pre-compressed mass, i.e. the so-called pre-pressed or preformed part, is then removed from the pre-press mold and inserted in a final press mold for final compression. However, what is disadvantageous here is that the pre-pressed part can quite easily be damaged when it is removed from the pre-press mold and when it is inserted into the final press mold, and when it is transferred between the pre-press mold and the press mold, respectively, partially rendering the pre-pressed part unsuitable for use, and reducing the quality of the finished friction linings, respectively.
From EP 591 637 A, an arrangement and a method for producing friction linings is known, where at first a pre-pressed part is produced in a pre-press mold, the pre-pressed part subsequently is transferred to a carrier for transportation and from the carrier then is transferred into a heated mold for final compression. Thus, also here the pre-pressed part must be removed from the pre-press mold and introduced into a press mold for final compression.
Furthermore, from AT 398 726 B, a similar method for producing friction linings is known, in which the friction lining mass at first is pre-compressed in an intermediate mold and subsequently is transferred to a press mold for final compression.
It is an object of the present invention to provide a method and an arrangement of the initially defined type for producing friction linings, wherein damaging of the pre-pressed part is largely avoided and, thus, a high product quality is ensured with a cost-effective production of the friction lining.
To achieve this object, the invention provides for a method of the initially defined type, in which it is provided that the pourable mass is pre-compressed already in the press mold and the pre-compressed mass is conveyed directly in the press mold to the press, where it is finally compressed. By pre-compressing the pourable mass already in the press mold, in which the mass subsequently is also subjected to the final compression, transferring of the pre-compressed mass, i.e. of the pre-pressed part, from a pre-press mold, or intermediate mold, respectively, into a final press mold is not required. Since the pourable mass thus is pre- and finally compressed merely in one single press mold, there is no risk of damaging the pre-pressed part during a transfer from a pre- or intermediate mold to a final compression mold. This, moreover, has the advantage that the risk of inserting the pre-pressed part eccentrically into the cavity of the final press mold, and thereby also of producing a low-quality friction lining, is avoided. Likewise, the press form is also substantially better filled as compared to charging it with a pre-pressed part with the yet non-compressed pourable mass. Moreover, an intermediate storage of pre-fabricated pre-pressed parts is not required.
Furthermore, the carrier plates, on which the pourable mass is compressed, usually have through-holes so as to ensure as tight a connection as possible between the friction lining mass and the carrier plate in terms of a shearing force stress. Since during the pre-compression of the mass in the press mold proper, there already also occurs a pre-compression on the carrier plate, possibly present through-holes of the carrier plate are filled with the pourable friction lining mass already during the pre-compression, again resulting in an improved connection of the friction lining with the carrier plate as well as in a particularly homogeneous structure of the finished friction linings.
With regard to simple transportation of the press mold, in particular for transferring the press mold filled with the pre-compressed mass to a final compression in the press, it is advantageous if the carrier plate(s) and the press mold are put on a base plate before the pourable mass is introduced into the press mold.
If a pre-compression mold is put on the press mold before the pourable mass is introduced into the press mold, a sufficiently large cavity will result for receiving the non-compressed pourable mass before the pourable mass is pre-compressed into the cavity of the press mold.
If the pre-compression mold is lifted off the press mold after pre-compression of the pourable mass and before the press mold with the pre-compressed mass is further conveyed, the press mold including the pre-compressed mass within the cavity of the press mold can be transported in a simple manner to the press for final compression.
On the other hand, for an efficient supply and pre-compression of the pourable mass, it is also advantageous if the pourable mass is introduced into the press mold under pre-compression with the help of a screw.
To enhance the connection between the friction lining mass and the carrier plate, it is suitable if an intermediate layer, preferably of graphite, phenol resin, metal chips, glass fibers or the like, in particular in the form of a mat, is applied to the carrier plate before the pourable mass is introduced into the press mold.
Instead of applying an intermediate layer in the form of a mat on the carrier plate, it may be advantageous if the pourable intermediate layer material is applied as an intermediate layer on the carrier plate before the introduction of the pourable mass and, preferably, is pre-compressed.
With regard to a simple and cost-effective production of the friction lining it is advantageous if, before the final compression of the mass, a closing plate is put on the mass which has been pre-compressed in the press mold.
If the pre-compressed mass is subjected to several, preferably independently adjustable, press procedures for the final compression, the desired product quality of the finished friction linings can be ensured in a simple manner via an individual regulation of the individual press procedures.
If the base plate, the press mold, and the closing plate are automatically separated from each other after completion of the friction lining, a fully automated process for producing the friction linings is created.
The arrangement of the initially defined type is characterized in that the pre-compression device has a receiving means for the press mold, and in that the conveying unit is adapted for transportation of the press mold with the mass pre-compressed therein, and the press is adapted for direct final compression of the pre-compressed mass in said press mold. Here, too, the advantages already mentioned in connection with the inventive method will result, since the pre-compressed mass is not removed from a separate pre-press mold and need not be transferred into a press mold provided for final compression, but the pre-compressing device already has a receiving means for the press mold proper, so that no separate pre-press mold need be provided.
If a displaceably mounted pre-compression mold is provided as the receiving means, the pre-compression mold can be put onto the press mold in a simple manner, before the non-compressed pourable mass is introduced into a cavity formed by the pre-compression mold and the cavity of the press mold.
In order to be able to produce different friction linings using the arrangement, without requiring complex re-fitting operations therefor, it is advantageous if different pre-compression molds are provided which can be selectively chosen, e.g. by means of a rotation device.
If the height of the press mold substantially corresponds to the height of the finished friction lining, a comparatively low, cost-effective press mold is provided, and by receiving the press mold in the pre-compressing device, a sufficiently large cavity is created in a simple manner for receiving the non-compressed pourable friction lining mass before the pre-compression.
With regard to a pre-compression realized with a simple construction, it is advantageous if a plunger displaceably mounted in the pre-compression mold is provided for pre-compressing.
If a reservoir including a displaceable chute is provided for introducing the pourable mass into the pre-compression mold, the pourable mass can be introduced in a simple manner from a reservoir connected to the chute into the cavity of the press mold.
As an alternative to a pre-compression device comprising a displaceable plunger, it is also possible that an axially shiftable screw which is rotatably mounted in a housing is provided as said pre-compression device. Such a compression device is described in detail in DE 196 27 440 C2, the disclosure of which thus is included herein.
In order to pre-compress a pourable intermediate layer material on a carrier plate, and to thus improve the connection between the friction lining mass and the carrier plate, it is advantageous if an intermediate layer compression device is provided for compression of a pourable intermediate layer material upstream of the pre-compression device, viewed in conveying direction. As an alternative, the pre-compression device could also have an associated further reservoir containing the intermediate layer material in addition to the reservoir for the friction lining mass, so that with the pre-compression device both the intermediate layer material and also the friction lining mass will be compressed.
For a intermediate layer compression device that is of simple and cost-effective construction, it is advantageous if the intermediate layer compression device substantially corresponds to the construction of the pre-compression device as previously described.
In order to be able to transport the press mold between the pre-compression device and the press in a simple way, it is suitable if a base plate is provided for supporting and carrying the press form as well as, optionally, the carrier plate(s) during transportation.
For as simple and cost-effective a final compression as possible, it is advantageous if the press form has an associated closing plate which is provided to be put onto the pre-compressed mass contained in the press mold.
If the side of the closing plate facing the pre-compressed mass has a plane surface, a particularly simple final compression of the type of a so-called flash mold method will result.
Alternatively, however, it is also possible that the side of the closing plate facing the pre-compressed mass comprises at least one plunger-like projection which enters the cavity in the press mold during pressing, resulting in a final compression of the type of a so-called positive mold method.
In order to prevent an emergence of friction lining mass during compressing from the cavity of the press mold in the direction of the carrier plate, it is advantageous if the connecting region between the press mold and the carrier plate is sealed by the application of force on the press mold during final pressing.
If several, preferably independently adjustable, press stations are provided for final compression, the desired quality of the finished friction linings can be ensured in a simple manner by regulating the individual presses.
If a device for automatically separating the press mold from the base plate and from the closing plate is provided, the entire compression of the friction lining can be carried out in fully automated manner by means of the arrangement according to the invention.
In order to be able to automatically separate from each other the base plate, the press mold and the closing plate in a simple manner, it is suitable if the device includes vertically shiftable rods which have at least three portions of different diameters, starting from the portion having the smallest diameter at the freely cantilevering end of the rods, so that the rods, in their upwardly shifted position, extend through corresponding passage openings in the base plate and in the press mold, respectively, with the portion(s) of smaller diameters, whereby a selective lifting of the closing plate and of the press mold from the base plate is achieved.
If retention arms are provided for maintaining the closing plate and the press mold in their lifted positions, the separated parts can be held after lowering of the rods for lifting the closing plate and the press mold and can be supplied in sequence to a transporting device.
In the following, the invention will be explained in more detail by way of preferred exemplary embodiments illustrated in the drawings, to which, however, it shall not be restricted. In detail, in the drawings,
a shows a top view on an arrangement similar to
a schematically shows a section of an alternative pre-compression device with a screw;
a shows a top view on a tool unit to be introduced into the arrangement according to
b shows a section according to line VIIIb-VIIIb of
c shows a section according to line VIIIc-VIIIc of
In
As is particularly visible from
In the pre-compression unit 3, a vertically displaceably mounted pre-compression mold 13 is provided which, after unit 12 has been positioned, is put onto the press mold 11. Thereby, from a cavity 11′ in the press mold 11 and from a cavity 13′ in the pre-compression mold 13, a mutual cavity is formed for receiving the non-compressed pourable friction lining mass 14 stored in a reservoir 2. Via a stirrer 2′ as well as a conveying and dosing unit, a pre-determined amount of friction lining mass 14 is introduced into the receiving means formed by cavities 11′ and 13′ by means of a chute 2″ whose lower end is pivoted to the upper opening of the pre-compression mold 13.
In order to make it possible to provide corresponding pre-compression molds 13 for different carrier plates 9 without any time-consuming retrofitting, e.g. four pre-compression molds 13 arranged offset by 90° relative to each other are mounted on a rotation device 3′ of the pre-compression unit 3. Accordingly, depending on the position of the rotation device 3′, a different pre-compression mold 13 can be inserted.
In the pre-compression unit 3, furthermore, a plunger 15 is provided which is displaceable within the pre-compression mold 13 so that—as is particularly visible in FIGS. 3 and 4—the friction lining mass 14 is pre-compressed on the carrier plate 9. During this pre-compression, also a pre-compression of the friction lining mass 14 occurs in the through holes 9′ (cf.
Alternatively to the
As can be seen from
Other than in the arrangement shown in
As can be seen from
However, on the other hand, as shown in
After the closing plate 17 has been laid on the pre-compressed mass 14, the entire unit arranged on the base plate 10 is transported into the press 4 for hot pressing for the purpose of a final compression, the press 4 having several press stations 21 (cf.
After having left the press 4, the tool unit 12—consisting of the base plate 10, the carrier plate 9 with the completely compressed friction lining mass 14, the press mold 11 and including the closing plate 17—is transported into the tool separating device 5 (cf. in particular
As is particularly visible from
In order to avoid an undesired lifting of the base plate 10, the base plate 10 is retained in the tool separating device 5 by two lateral hold-down webs 25. To separate the closing plate 17 from the press mold 11, hold-down means 26 are provided.
As is particularly visible from
Then the retaining arms 27 are lowered in the direction of arrow 27′ so that the press mold 11 is lowered onto the conveying device 7 and is moved on with the conveying device 7 to an ejection device 5′.
In the ejection device 5′, the final-compressed friction lining mass 14 including the carrier plate 9 is ejected from the cavity 11′ of the press mold 11 by an ejector 29 which is shifted in the direction of arrow 29′, and subsequently is also transported in the direction of the returning device.
Finally, also the closing plate 17 is lowered onto the conveying device 7 and moved to the returning device, so that the base plate 10 as well as the press mold 11 and the closing plate 17 are cleaned and sprayed in a cleaning and spraying unit 6. With the aid of the conveying device 7, the base plate 10, the press mold 11 as well as the closing plate 17 thus are conveyed in a circle so that they can be provided for another run through the production process when a finished friction lining has been produced.
Of course, the press mold 11 may have any desired number of cavities 11′, and also different devices can be provided for the pre- and final compressions. What is essential is merely that the friction lining mass is pre-compressed already in the press mold 11 proper, before the press mold 11 is transported to the hot press 4 for the final compression.
Number | Date | Country | Kind |
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A 138/2004 | Jan 2004 | AT | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/AT05/00027 | 1/31/2005 | WO | 00 | 4/25/2008 |