DE3114435A1 - BRAKE PAD AND METHOD FOR THE PRODUCTION THEREOF - Google Patents

Description

311443b

The invention relates to friction or brake pads for disc brakes and a method for making such articles.

In the case of the brake pads for disc brakes, the ones in question here Art is a riveted design that consists of a Carrier plate or a shoe made of a metal plate with a usual thickness of about 3, U mm to 6.1 mm (o, 135 to 0.25 inches) and a relatively thick pad of friction material attached thereto with rivets.

So far, the friction lining on the shoe has usually been riveted partly hollow, fastened, inserted into aligned bores or rivet holes in the brake shoe and in the friction lining became. Each bore had a very narrow inner shoulder for corresponding engagement with either the rivet head or with the compressed shaft of the rivet riveted over it.

It is known that the large Scherb.eanspruchungen withstood by the brake pads of disc brakes in operation make sure that the rivets in it come loose as you work and ultimately the deterioration and destruction of the Accelerate the friction lining. Such a covering generally consists of asbestos and resin, optionally 10 or more other ingredients are mixed in to provide the necessary frictional properties. In dependence of the special composition can therefore be compared to friction linings in terms of their strength and resistance Shear forces vary within a considerable range.

To some extent, the problems associated with loosening rivets in the brake shoe have been with a brake shoe can solve according to US application 06/071 475. One of those

Brake shoe has integrally formed, extruded rivets that are received within rivet holes in the friction lining and riveted over shoulders within the rivet holes. While a brake shoe with integral rivets is a has shown some improvement in friction pads for disc brakes, so the tendency of shoulders in the Do not reduce the friction lining sufficiently so that it does not dissolve under shear stresses. It is It is essential that the shoulder is typically 1.5mm (0.06 inches) thick.

It is also essential that it has not previously been feasible to have the rivet holes in the friction lining simultaneously with the molding of the friction lining itself, since the friction lining itself, as stated above, consists of a large number of components with different properties that cause it to shrink unevenly during its cooling process and thus tend to distort the shoulders, resulting in an irregular fit for the rivets in the rivet holes. As a result, the rivet holes in the friction lining had to be drilled, instead of to mold them, which of course rivet holes with unmachined Left walls.

The object of the invention is therefore to provide brake pads for disc brakes and to specify a method for producing such brake pads that are more economical than before can be produced and are more resistant to the destructive effects of shear stresses during operation be exercised.

According to the invention, there are brake pads for disc brakes specified, which have a shoe and a friction lining, which are connected to one another with rivets that are integral are formed with the shoe and extend into bores in the friction lining and are secured therein in such a way that that they reduce the tendency of the rivets to loosen in them.

More precisely, according to the invention, brake pads are specified which have a covering with bores for rivets, which in contrast to the conventional arrangements are free of shoulders.

According to the invention, a method for the production of brake pads is specified, which is designed so that the rivet holes need not be drilled in the friction lining, but rather molded into it, so that the friction lining further strengthens and at the same time eliminates the machining that was otherwise necessary for the production of rivet holes.

As already explained, according to the invention, a brake shoe with hollow, integral rivets of the type mentioned at the outset Type used according to the above-mentioned US application. According to the invention, a friction lining is used which is suitably adapted to the shoe and is therefore provided with corresponding holes for the intagral, hollow rivets protruding from the brake shoe.

The shoe and the friction lining have interfaces that come into contact with one another, while the rivet holes in the friction lining, in which the hollow rivets protrude, is provided with zones that

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starting from the interface of the friction lining in Progressively widen or widen conically towards the opposite surface. It seems reasonable that the expansion or conical expansion need not be continuous to the opposite surface.

The friction lining is in the form of an overlay on the shoe applied so that the corresponding interfaces closely against each other abut, and the hollow rivets of the shoe are adapted to the rivet holes of the friction lining, with parts of them clearly .in the widening or conically widening Extend zones into it.

After assembling the friction lining and shoe the above described The shafts of the hollow rivets extending into the widened zones are widened or pushed apart, in order to be in a tightly fitted, abutting and wedging position with respect to the conically widening zones of the Rivet holes. To widen.

The zones in the friction lining are preferably widened or conically widened at a height that is at the interface or starts near it. This is the expansion or expansion preferably conical, with a preferred one Embodiment is laid out so that the walls are steep and below are inclined at an angle of about 10 ° with respect to the axis of the rivet holes.

There are already known brakes for vehicles in which Rivets with tapered or conical heads can be used, which, however, have a different structure than those according to the invention Brake pads.

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From US-PS 17 11 6 02, for example, an arrangement with a plate c is known, which has a corresponding friction lining owns, the with countersunk rivets el within a cup-shaped Part c2 is fastened from sheet metal, which in turn is screwed to a brake shoe cU. There are those Rivets are clearly separated from, instead of integral with the Plate c2, and while there conical heads are shown in the drawing, there is no other indication than that the head part of the rivet el is solid or solid.

A substantially similar arrangement is found in US Pat. No. 2k 38 H83, showing rivets 16 with conical heads at their respective ends which connect a brake block 14 and a brake head 2. As in the above-mentioned document, there is no reference whatsoever to the special type of rivets 16, so that, based on the description and drawing there, it can be assumed that the rivets are solid.

The US-PS 20 67 677 and US-PS 37 67 018 show hollow rivets, with wide beveled heads embedded in the friction lining material are shaped with the hollow portion then pressed or upset over the inner surface of the brake shoe, as indicated by the reference numeral 16 in Fig. 3 (see. Column 2, line 8 of US-PS 20 67 677).

In CA-PS 658 959 brakes are described in which .zentral perforated discs of friction material 22 are encased in containers 18 and 20 which are attached to an annular support by means of Hollow rivets are attached, the respective ends of which are flared, essentially for the purpose of surrounding the containers 18 and 20 to hold on the carrier 12 and to press against the friction material, as can be seen most clearly from FIGS. 3 and results.

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The main difference between the rivets of the invention Brake pads and those according to the literature reference results from the text in column 1, lines 17 to 25, where emphasis It should be noted that the friction material need not be self-supporting there, so that there is the requirement results in using containers.

In this respect, there are serious differences compared to the one according to the invention Recorded training, since the friction lining in the brake pads according to the invention is self-supporting and so designed is that it can be riveted onto a support plate or a brake shoe.

The invention is explained below with reference to the description of exemplary embodiments and explained in more detail with reference to the accompanying drawing. The drawing shows in

Fig. 1 is a perspective schematic representation of a brake pad according to the invention, wherein Parts of the brake lining are broken away to explain details;

Fig. 2 is an exploded enlarged view in section of part of the friction lining and a corresponding part of a carrier plate in a disassembled state; and in

FIG. 3 shows an illustration to explain the parts according to FIG. 2 in the assembled state.

In the description below, aspects of the process and the product are intermingled in order to facilitate the understanding of the To facilitate the invention, whereby the process differs in some places from the description of the product and vice versa

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Product will emerge better in some places from the description of the process.

As shown in the drawing, the brake pad D for a disc brake according to the invention consists of a carrier plate or a brake shoe P and a matching block of friction lining L, which is attached to the brake shoe P, the corresponding interfaces 2 and k tightly and intimately against each other which is essential for the proper function and long service life of the brake pad D. The carrier plate or the brake shoe P has hollow rivets 6 which extend integrally from its interface 2; such a hollow rivet 6 is shown in detail in cross section in ELg. and 3 .the drawing shown on an enlarged scale.

In general, the brake shoe P usually consists of mild steel with an average thickness of about 3.4 mm to 6.4 mm (0.135 to 0.25 inches).

In the context of the above description, the term "Integrally" indicate that the hollow rivets 6 are formed from the material which forms the brake shoe P, wherein they are preferably are formed by extruding a sufficient amount of brake shoe material through a preformed guide hole, to form rivets of the type in question and shown.

For the sake of clarity, it seems expedient and essential at this point to explain in more detail what is meant by the term "extruded" Rivet "is understood. The term" extrude "is sometimes used erroneously to describe something in reality is a simple drawing or crimping process, the edge zone of which is formed in a thin sheet of metal

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Hole is rotated perpendicular to the plane of the sheet to form a flange around the hole.

While the extruded hollow rivet 6 has walls 8 that also To form a flange around a hole, the fact is that the substance of the walls 8 is largely taken from the sides of the hole becomes, as is evident from the drawing. The hollow rivet 6 thus effectively extends clearly into the Brake shoe P and merges integrally into this, whereby a firm rooting or anchoring in this brake shoe is created, and the hollow rivet made of pre-pressed material of the brake shoe itself.

The advantages of an extruded hollow rivet over a conventional one drawn flange of the type indicated above are diverse, the following aspects being addressed below should:

First of all it is, apart from the stated strong Anchoring, obviously difficult, if not practically impossible, steel the thickness of a brake shoe as here considered Type of flanging without simultaneously "piling up" metal around the base of the flange or rivet, which is in the present context deft would prevent the friction lining L from sitting flat on the brake shoe P in a very annoying manner.

Also, proper extrusion is usually best suitable to provide the hollow rivets 6 with walls of uniform thickness, which is also important for the function of the products according to the invention, as is readily apparent from the context.

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Finally, the extrusion as described and envisaged herein can usually be a sturdy, walled rivet of uniform thickness and dimensions best suited to meet the rather severe demands of the service suffice.

Each of the hollow rivets 6 has a straight cylindrical wall 8 which from the interface 2 of the brake shoe P protrudes perpendicularly. The hollow rivet 6 is finally from an annular shoulder 10 within a cylindrical recess 12 is formed which extends from the outer surface IU of the brake shoe P into its interior.

For orientation purposes it should be pointed out that the annular shoulder 10 is arranged closer to the interface 2 of the brake shoe P than on the opposite outer surface IU. The depth 'of the recess 12 between the outer surface IU and the annular shoulder 10 thus forms a major part of the total thickness of the brake shoe P.

As a general statement, which is in no way to be interpreted as restrictive, the hollow rivet 6 can extend over the interface 2 by about 3 mm of the brake shoe P protrude having a thickness of that described above Art, which is about 60% or less of the thickness of the brake shoe.

In Fig. 1, the brake shoe P is in the assembled state with the brake lining L shown, which is provided with rivet holes 20, in which the integral hollow rivets 6 of the brake shoe P protrude.

According to the invention, the rivet holes 20 in the friction lining L are designed so that they widen from its interface U. or widen, the interface U necessarily being in

tight and intimate contact with the interface 2 of the brake shoe P stands.

It should thus be noted that the integral hollow rivets 6 of the brake shoe P protrude into the rivet holes 20 in the friction lining L, which widen towards the opposite surface 22 or widen what the rivet holes 20 are approximately V-shaped Gives cross-section. As already explained above, the depth of penetration of the hollow rivets 6 into the rivet holes 20 is approximately 3 mm or less. As already mentioned, the walls 24 of the rivet holes 20 are preferably at an angle of approximately 10 ° inclined with respect to its axis and smooth, i.e. free from shoulders.

The friction lining L for the brake pad according to the invention can be made from a large number of materials in a wide variety of compositions be designed to contain asbestos, binders, resins, graphite, Contain oxides, metal particles, barytes and friction elements.

In accordance with normal practice, the block forming the friction lining L is molded; the rivet holes 20 are also made simultaneously shaped therewith and of course positioned to receive the rivets of the brake shoe P when the brake pad D is assembled as shown in Figs.

A very important advantage compared to the state of the art, which results from the shaping of the rivet holes 20 in the friction lining L, is that all rivet holes 20 with a Layer or skin are left that is more resistant to the damaging effects of shear forces than that "fresh" or raw core of the friction lining L, which would be exposed if the rivet holes 20 were drilled or otherwise in the friction lining L would be cut, instead of producing it with a molding process.

The shaping of the rivet holes 20 is of course made possible by the fact that in the manner described for an expansion or enlargement, eliminating the shoulders or ribs that were used in the prior art to seat the Rivets are provided. That means, in the past it was important to have the shoulders or ribs really flat surfaces to engage with the conventional ones Rivets formed. This requirement made it impractical for the shoulders or rivets to mold into conventional friction linings because of the uneven shrinkage of the various components after the molding process. This inability, in turn, made it necessary that the shoulders were made by drilling into the friction lining, which for the reasons given led to the friction lining on this point has been weakened.

The prior art reinforcing rib or shoulder also suffered, of course, from the further disadvantage that this part was usually very thin, usually about 1.5 mm (€ .06 inches) thick, thus having a tendency to to disintegrate under the stresses and strains that the brake pad is exposed during operation.

The brake shoe P and the brake lining L are assembled, by placing them with their interfaces 2 and 4 in close contact with one another, the hollow rivets 6 clearly extend from the brake shoe P into the smooth, widening zones of the rivet holes 20 in the brake lining L. The walls 8 the hollow rivets 6 are widened or widened with a tool, not shown, to them substantially over their extend and wedge their entire length so that they are in mated, close frictional contact with the widening or

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conically widening walls 24 of the rivet holes 20 come.

Under normal circumstances it should not be necessary to have an anvil or similar counter pressure arrangement behind the Brake shoe P to be provided when expanding or wedging the walls 8 of the hollow rivets 6 '.

It seems understandable that the ductility or deformability of the brake shoe material normally plays a role in widening or widening the hollow rivets 6 and thus also with regard to it on the conical widening of the rivet holes 20 in the friction or brake lining L.

In general, however, if the brake shoe P is made of mild steel, as is believed here, its hollow rivets .6 are readily in close frictional engagement with the walls 24 of the Rivet holes 20 stretchable and deformable, the walls 24 of the rivet holes 20 at an angle of about 10 ° to the axis of the Rivet holes 20 are arranged inclined.

On the other hand, it has been found that the walls 8 of the hollow rivets 6 made from a mild steel backing plate would have a tendency to tear when expanded or deformed into rivet holes 20, the walls of which are inclined at an angle of more than 20 ° with respect to the axis of the rivet holes 20.

The invention is based to a not inconsiderable extent on the fact that the wedging of a hollow rivet on an inclined or inclined surface of the type in question here is quite excellent Results in terms of the there — through increased holding power.

Thus, the performance of a brake pad according to the invention is in comparison tests with a standard brake pad for disc brakes has been investigated.

In such an investigation it was found that a brake pad according to the invention was able to withstand shear stresses withstand up to about 49 bar (700 PSI). In comparison, it has been found that in cases where a friction or brake lining is attached to a brake shoe with separate rivets the arrangement was only able to withstand shear stresses, at which the upper limit was approximately 31.5 bar (450 PSI).

It is thus seen that the brake pads according to the invention have an improvement of approximately 70% in terms of resistance against destruction by shear stress.

In conventional brake pads for disc brakes it was also found that the rivet shafts invariably up to possessed to some extent, albeit minimal, play in the rivet holes, often resulting in significant wear and tear finally led to the undesired destruction or dissolution of the ■ clearing. In contrast, the inventive Brake pad designed as a relatively homogeneous unit, since each rivet is not only formed integrally with the brake shoe P, but also widened within the rivet hole of the brake lining L is widened and wedged in it relatively immovably, which gives the brake shoe P a firm hold on the friction or Brake lining L gives what is evident by the smoothness of the flared walls 24 of the rivet holes 20 and, consequently, the absence of projections such as the conventional ones Shoulders. According to the invention

thus a brake pad and a method for its manufacture are specified, which have a number of advantages are explained in more detail below.

First of all, the method of making the brake pads does not require drilling holes in the friction material. Instead of this the required holes can be made by one molding process at the time when the entire brake pad is shaped. In addition, the inner rivet seats come in the rivet holes in elimination and thus provide a larger area of intervention.

In addition, since no separate rivets are required, the actual fastening process can be not only faster, but also faster can also be carried out with less equipment and devices than was previously the case.

Finally, it should be pointed out that in the aids envisaged here for widening or expanding the Hollow rivets in wedging engagement with the widening in the Rivet holes of the friction or brake lining on the one hand a common obstacle is cleared, namely the vulnerable conventional rivet seat, and on the other hand the hollow rivet comes at Brake pad according to the invention over its entire height with the Friction or brake lining in engagement, and not just with a narrow edge, which in the prior art with the shoulder or the rivet seat is engaged.

It is also important in this context that apart from the fact that the hollow rivet comes into engagement with the brake lining with its entire height, the manner particularly advantageous is how the hollow rivets are engaged.

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More precisely, the widening or expansion of the present hollow rivets in the conically widening rivet hole, to provide a tight and flush fit in it, gives it great resistance, not only to axial forces, but also with regard to radial forces in order to prevent lateral play of the rivet holes. In addition, it appears that the widening of the rivet will wedge into engagement with the expanding walls of the rivet hole effectively ensures that the brake lining is pressed close to the brake shoe and therefore very is resistant to separation from it.

In contrast, the usual head compression or riveting with conventional rivets contributed little or nothing to a to prevent radial separation or displacement of the parts of the brake pad relative to one another, and in fact had none Driving action, as is the case with the arrangement according to the invention the case is.

It should be noted that the use of the term "smooth" in connection with the rivet holes 20 in the Brake lining L is used to define a rivet hole that is devoid of protrusions such as rivet seats in the prior art or other protrusions or indentations which allow a relatively complete and tight fit engagement of an expanded Wall 8 of the hollow rivet 6 with the widening walls 24 of a rivet hole 20 would thwart, such Complete and intimate engagement is an essential element in the advantages achieved by the invention.

Claims (10)

311U35 : PATENT LAWYERS "FOPP & SAJDA MARIA-THERESIA-STRASSE 30, 8000 MUNICH 80 POSTAL ADDRESS: POSTFACH 860624, D-8000 MUNICH 86 Patent Attorneys Popp & Sajda, Postfach 860624, D-8000 Munich 86 Dr. Eugene Popp Dipl.-Ing., Dipl.-Wirt.-Ing. WoIfE. Sajda Dipl.-Phys. LEAR SIEGLER, INC. Telephone (089) 981802 South Bundy Drive ™ ^ex522862 ,? P ^ezd _t> , .. *, ". ... _ ^J. . j. . Telegrams Epopat Munich Santa Monxca, California
United States of America Your reference Our reference date IET SÄ 1329 SS 9 :. April 1981 Brake pad and
Process for its manufacture Claims Brake pad for disc brakes or the like, marked by a brake shoe (P) in the form of a metal plate, an adapted brake lining (L) and Rivets (6) for the mutual fastening of the brake shoe (P) and the brake lining (L), so that their interfaces (2, U) lie tightly against one another, the rivets (6) being hollow and in rivet holes (20) are widened in the brake lining (L) and wedge the brake lining (L) against the brake shoe (P). '"::": =. - "- Ί 311443b - 2 - 2. Brake pad according to claim 1, characterized in that the rivets (6) are formed integrally with the brake shoe (P) are. 3. Brake pad according to claim 1 or 2, characterized in that that the rivet holes (20) in the brake lining (L) have smooth walls (24) and from the interface (4) of the Start widening the brake lining (L). 4. Brake pad according to one of claims 1 to 3, characterized in that the walls (24) of the rivet holes (20) in the brake lining (L) widen conically from the interface (4). 5. Brake pad according to one of claims 1 to 4, characterized that the walls (24) of the rivet holes (20) in the brake lining (L) have a V-shaped cross-section and are inclined at an angle of about 10 ° with respect to the vertical axis of the rivet holes (20). 6. Brake pad according to one of claims 1 to 5, characterized that the rivets (6, 8) are formed as molded projections of the brake shoe (P). 7. Process for the manufacture of brake pads for disc brakes or the like, characterized by the following process steps: Manufacture of a brake shoe from a plate-shaped material which has an interface SD such as integrally formed on it Has hollow rivets that protrude over the interfaceζ Manufacture of an adapted brake lining with an interface and smooth-walled holes for the hollow rivets in the brake lining between the interface and the opposite Surface, -. _: -: .- ;. 311U35 Installation of brake lining zones in the rivet holes, which away from the interface towards the opposite Widen the surface, Assemble the brake shoe and brake lining so that the respective interfaces are in close contact with one another come and the hollow rivets of the brake shoe are inserted into the rivet holes, where they widened into the Zones of the brake lining extend, and widening or spreading of the hollow rivets in the widened Zones so that they expand and adapt to the contours of these zones and thereby engage in intimate friction wedge to the walls of the zones. 8. The method according to claim 7, characterized in that the widening zones of the rivet holes in the brake lining be conical. 9. The method according to claim 7 or 8, characterized in that the walls of the widening zones in the brake lining be formed inclined at an angle of about 10 ° relative to the axis of the rivet holes. 10. The method according to any one of claims 1 to 9, characterized that the expansion of the zones in the brake lining is formed so that they are at a height in the immediate Near the boundary surface of the boundary layer begins.