MXPA99005617A

MXPA99005617A - Friction lining attachments

Info

Publication number: MXPA99005617A
Application number: MXPA/A/1999/005617A
Authority: MX
Inventors: John Young Brett
Original assignee: Hibond Research Pty Ltd; John Young Brett
Priority date: 1996-12-18
Filing date: 1999-06-16
Publication date: 2000-05-01

Abstract

An attachment between segments (12) of a friction lining material and a brake shoe (11), in which the lining (12) is attached to the brake shoe (11) by a plurality of keying elements (16) attached by screws (17) to the brake shoe (11), and cooperating with a plurality of associated grooves (18) in the lining (12) in such a manner as to prevent the lining (12) from becoming detached from the brake shoe (11). The keying elements (16) being retained within their associated grooves (18) whereby there will be no, or a limited amount of, relative movement between the lining (12) and the brake shoe (11) in any direction.

Description

FRICTION COATING ADDITION TECHNICAL FIELD This invention relates to the attachment of friction liners to support plates, such as those that can be used in a vehicle or other machine braking systems, clutch mechanisms, or other mechanisms where friction linings should be used. fixed to a support plate, disc or brake shoe. For the purpose of this specification reference will be made principally to the attachment of the friction lining material to base plates of brake pads for vehicles, particularly heavy-duty vehicles such as buses, trucks and trailers, which due to their weight and In the area in which they may be required to operate, they must have the secure fastening of the friction linings over the brake shoes to prevent brake malfunction and the resulting consequences of the same. The invention is also applicable to other vehicles such as automobiles, motorcycles, trains, off-road equipment, moving equipment on the ground, elevators and braking systems of airplanes, and clutch mechanisms where applicable, as well as other machinery in where the brake or clutch mechanisms may be necessary. REF .: 30602 Background Art Conventional abutments between friction linings and support plates, such as between brake linings and base plates in brake shoes, have involved the use of rivets that couple the linings to the support plates . The heads of the rivets on the side of the cladding of the abutment are received in recessed holes, and maintain the union until such time as the friction linings wear to such an extent that the heads of the rivets and the associated braking surface, such as a surface of a brake drum or brake disc, are sufficiently close and replacement of the friction linings is required. A well-known problem with such attachments is that there is an accumulation of dust on the rivet cavities which is the result of the abrasive action of the coatings against the associated braking surfaces causing corrosion or other damage to the braking surface requiring machining maintenance from time to time to repair damage to drum or brake disc. Furthermore, in order to securely join the linings to the support plates (base plates), specialized equipment is often required and a considerable number of rivets may be required which are added to the expenses, both in the parts and in the work, in the manufacture and maintenance of the brake, clutch or equivalent component. An alternative fixation is known using direct bonding of the coatings to the support plates without the need for rivets and using hot or cold bonding agents, which due to advances in the technology of the bonding agents have allowed the fixation reliable in most cases. However, in some severe heavy duty applications, such as truck braking systems, trailers, and more particularly buses where safety factors are particularly critical, there are perceived problems with respect to the shedding of friction linings ( brake linings) for the support plates (brake bases) and although brake failures resulting from such detachments are very rare, there is some concern on the part of truck and bus operators to use joined brake linings in some applications of severe service. The main possible cause of brake malfunction with joining techniques is that when a brake lining wears, and as a result of thinning, the heat generated during extreme braking operations is driven more quickly to the lining interface and the support plate, whereby the hot or cold bonding agent can be adversely affected to the extent that the bonding action fails and the coating is separated from the support plate. In the past it has been proposed to provide an abutment between a friction liner and a support plate, in which the liner is fastened to the support plate by one or more fasteners attached to the support plate and cooperating with one or more associated grooves in the coating in such a way as to prevent the coating from detaching from the support plates. * One such attachment is described in the Australian patent specification no. 149358 entitled "Improvements in or Related to a Clutch or Brake Mechanism" and related to a patent granted to Hans Rangvald Amundsen (which is hereinafter referred to as the Amundsen patent). However, such proposals have involved the use of stop elements which extend completely through the support plate, as do the associated grooves in the skin, thereby leading to the possibility of the skin moving laterally, or still leaving, of the support plate under certain circumstances. Therefore, it is an object of the present invention to provide an abutment between a friction liner and a support plate which eliminates, or at least reduces, the above problems with the riveted, joined, or stopped and grooved abutments, and particular with respect to the latter, any possibility that existed of the relative lateral movement in any degree in the coating and the support plate.

BRIEF DESCRIPTION OF THE INVENTION According to the present invention, an abutment is provided between a friction coating material and a support plate, in which the coating is attached to the support plate by means of a plurality of attached fasteners to the support plate and which cooperates with a plurality of recessed slots in the coating in such a way as to prevent the coating from detaching from the support plate, the cavities are formed in the face of the coating in contact with the support plate and end near the other face of the cladding, wherein the wall of at least one of the cavities completely surrounds and is engaged by its associated arresting elements and / or at least two cavities extend from the opposite edges of the cladding and partially through of the lining with the internal ends of the cavities forming contacts against which the arresting elements are coupled as ociados, and so in any case there will be no, or there will be a limited amount, of a relative movement between the liner and the support plate in any direction. Preferably some of the peripheral edges of the stop element are designed so that they are wedge-shaped and the edges of their associated cavities are correspondingly formed, whereby a larger cross-section contact area is created. resulting in a higher retention of the coating compared to conventional association methods, and also due to a difference in the coefficients of expansion between the material of the arresting elements and the friction coating material, the higher the temperature under the which operates the major attachment the degree of clamping between the stop element and the friction lining, and at higher friction the liner is pulled against the support plate. In one embodiment, at least some of the stop elements are elongated and received in corresponding elongated slots and at least some of those stop elements and their associated slots extend only partially through the interface between the support plate and the liner of friction on one side of it and opening through that side; and at least those other stopping elements and associated slots also extend only partially through the interface from the other side thereof and opening through that side. In another embodiment at least one of the arresting elements is a suitably shaped element received in a cavity that resides entirely within the friction coating material. Preferably the stop elements are attached to the support plate by screws, bolts or rivets which extend through the openings in the support plates and towards the stop elements after the coating has been placed on the plate of support. In an alternative mode even more the attachment can be formed by a combination of screws, bolts or rivets and joined or cemented. In a still further alternative embodiment the stopping elements can be molded into the facing material at the time of molding the coatings. Possibly a bonding agent between the coating and the support plate can also be provided to improve the bonding of the coating to the plate. The invention contemplates the combination of a friction coating having at least one cavity and a stop element for the association between them as defined above.

BRIEF DESCRIPTION OF THE DRAWINGS Two preferred embodiments of the invention will now be described, and several amplifications thereof, with reference to the accompanying drawings, in which; Figure 1 is a perspective view of the partial exploded view from below of a typical brake shoe incorporating the first embodiment of the present invention. Figure 2 is a plan view from the top of a stop element used in the preferred embodiment of Figure 1. Figure 3 is an elevation view from one end of the stop element of Figure 2., Figure 4 is a perspective view from the top of the stop element of Figure 2, Figure 5 is a perspective view from the bottom of the stop element of Figure 2, Figure 6 is a view in cross section through a stop element for use in a second embodiment of the invention, Figure 7 is a plan view of the stop element of Figure 6, and Figure 8 is a cross sectional view of a skin that it has the arrest elements of Figures 6 and 7 received in the cavities in the coating.

BEST MODES FOR CARRYING OUT THE INVENTION Those preferred embodiments of the invention relate to a brake shoe for a vehicle, which shoe is of arcuate configuration to cooperate with the internal braking surface of a cylindrical brake drum. In the first preferred embodiment, the brake shoe, designated 10, comprises an arcuate-shaped elongate brake plate 11 to which is applied, in this case a pair of arcuate-shaped brake lining segments 12. The side radially internal of the brake shoe 11 contains a pair of shoe webs 14 extending along the length and beyond the ends of the brake plate, and spaced apart in parallel relation, and which also have openings 15 to its through at either end for fixing the brake actuation mechanism as is conventional with vehicle braking systems. Up to this point the typical brake shoe described is of a conventional type, and to which in the past, the brake lining segments were riveted or joined to the brake plate as discussed above. According to this first preferred embodiment of the invention, the use of a plurality of rivets to directly attach the segments of the respective brake lining 12 to the brake shoe, are distributed with, and instead of the elongated stop elements 16 stamped , pressed, laminated or otherwise formed of flat metal plate. In this example six such elements are provided for each covering segment (three on each lateral side thereof), and fastened using a single screw 17 for each stop element, unlike the Amundsen patent where two were required Bolts Also, unlike the Amundsen patent, the arresting elements only extend partially across the width of the brake plate and cooperate in a stopping action with the associated slots 18 formed in a correspondingly corresponding manner across the inner side of the brake plate. respective coatings segment. In this preferred embodiment, the stopping elements 16 are of wedge-shaped configuration inclined inwards towards the brake plate 11 and the slots 18 are engageable to prevent the detachment of the elements of the plate coating from the plate. Brake. The segments of the coating placed with the stop elements are placed in position on the brake plate, after the screws 17 are inserted through the openings 19 in the brake plate 11 and in threaded engagement with the corresponding holes 20. in the stop elements, which can be drilled or otherwise formed to receive appropriate screws. Alternatively the holes 20 may be threaded holes formed in solid stop elements and bolts replaced by bolts. In this preferred embodiment as mentioned above the stop elements are wedge-shaped since their periphery 16a is inclined, typically at an angle of 45 °, and the peripheries of their associated cavities are sloped accordingly, the effect of which is that a larger cross-section contact area is created resulting in a higher retention of the cladding compared to conventional clamping methods, and also, due to differences in the coefficients of expansion between the metal of the arresting elements and the material of the brake lining segments, the higher the temperature under which the brake system operates, the greater the degree of clamping between the arresting elements and the lining segments and the lining segments are more strongly pulled against the brake shoe. Brake. Such an effect is not possible with the stopping elements T shaped Amundsen Patent, but also relatively slim flanges defining the T-shaped grooves within the .revestimiento Amundsen Patent likely to break under pressure. Also for the purposes of this preferred embodiment the brake plate 11 may be a conventional brake plate having two laterally spaced openings 19 which would normally receive rivets in accordance with normal practice, but we have found that when testing the existing brake systems using the present invention only one fastening screw 17 is required and thus the additional opening is not required. In the case of the brake plates specifically manufactured for the purposes of the present invention, the opening 19 will not be required. Calculations have shown that the area of the surfaces cooperating between the arresting elements 16 and the slot 18 will be significantly larger than those provided by the normal number of rivets used to join the segments of the lining in the conventional lining attachments. The optimum number of arresting elements of the means for holding them, such as screws 17 or bolts, will finally be determined by the application, physical characteristics of the coating and the shear force of the fastening elements. The present invention resists lateral movement of the cladding elements since it involves the use of grooves formed only partially through the inner side of the respective cladding segments on one side and the other, and the arresting elements are inserted from both sides , so that, in addition to preventing the movement of the recess elements along the length of the brake plate, the liner segments will also be prevented from moving laterally of the brake plate. In addition, the joint between the lining segments 12 and the brake plate can be improved by providing a bonding agent (either hot or cold bonding) between the interface between the lining segments and the brake plate. In this embodiment of the invention, the ends of the stop elements 16 are formed in a semicircular shape to be coupled to the semicircular internal ends of the associated slots 18 which would result from a wedge-shaped circular loop cutter that is one of the most common forms. Conveniently forming the wedge-shaped grooves 18. Alternatively the internal ends of the stopping elements and their associated grooves may simply be square as their outer ends. In the case of solid stopping elements, they may be forged from, for example, high traction broach, while in an even more alternative embodiment of the invention the majority of the length of the stopping elements may be cut from a length of an extrusion. formed more conveniently to form elongate rectangular stopping elements and if semicircular ends thereof are required those could be provided by molded plastic parts formed separately.

The length of the stop elements 16 and the associated slots 18 extending laterally from either side of the brake shoe can vary on either side of the brake shoe and be such that one can overlap one on one side adjacent to the other side, thereby increasing the resistance against separation of the coating along the length of the brake plate. Referring to Figures 6, 7 and 8 of the drawings, in a second preferred embodiment of the invention the stop elements are punched circular button-shaped wedges 21 of a suitable metal section such as steel or metal alloys, for example bronze. , using a punch which will form the button in a concave shape as shown in Figure 6. The degree of concavity may vary depending on the particular application. The buttons 21 are subsequently inserted into the cavities 22 provided in the facing material 23 and of inwardly and outwardly inclined configuration as shown in Figure 8, with the buttons being pressed flat within the cavities so, due to its original concavity, its inner side is made to flare or flare out to allow the firm wedging of the buttons inside the cavities. The buttons 21 can be formed with a ribbed or bubbled edge or circumference to increase the grip on the friction material within the cavities. The diameter and thickness of the buttons can vary depending on the particular application, as could be the metals of which they are formed, although in addition to being formed with punches, the buttons can be machined or molded in the required form. Either before or after the buttons are pressed into the cavities, they can have holes drilled, punched or otherwise formed therein to receive screws (not shown) for attaching them to the brake plate via a hole through the brake plate. The fixation can be achieved alternatively by grooved or threaded holes to receive screws or resist welded studs or special tubular rivets or a milling type. The holes can be formed during the punching, machining or molding of the button. The stop buttons or elements may be of other shapes, such as square, rectangular, hexagonal or other polygonal shapes and may be knurled appropriately, grooved or otherwise formed to increase their grip on the friction material. As an alternative to interference fit or coining of the buttons in their respective cavities they can be joined or waxed in their position, or a combination of screws, bolts and rivets and joint or cementing. In a further alternative, the buttons can be molded into the friction lining material when the liner is molded. The buttons or stop elements of any of the above embodiments may be formed of steel, metal alloys, plastics or other suitable compositions.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, k is the conventional one for the manufacture of the objects to which it refers.

Claims

CLAIMS • Having described the invention as above, the content of the following claims is claimed as property:

1. An attachment between a friction lining material and a support plate, characterized in that in which the liner is attached to the support plate by means of a plurality of stop elements attached to the support plate and cooperate with a plurality of Associated cavities in the coating in such a way as to prevent the coating from detaching from the support plate, the cavities are formed in the face of the coating in contact with the support plate and end up near the other face of the coating, where the The wall of at least one of the cavities completely surrounds and is coupled by its associated stop element and / or at least the cavities extend from the opposite edges of the liner and partially through the lining with the inner ends of the cavities forming contacts against the lugs. which are coupled their associated detention elements, and so in any case there will be no or there will be a limited, relative movement between the liner and the support plate in any direction. The attachment according to claim 1, characterized in that some of the peripheral edges of the stop elements are designed to be wedge-shaped and the edges of their associated cavities are formed correspondingly, therefore, it is created a larger cross-section contact area resulting in a higher retention of the coating compared to conventional clamping methods, and also due to a difference in the coefficients of expansion between the material of the stop element and the cladding material friction, the higher the temperature under which the attachment operates the greater the degree of clamping between the stop element and the friction lining, and the friction lining is pulled more strongly against the support plate. The attachment according to claim 1 or 2, characterized in that at least one of the stop elements is elongated and received in a corresponding elongated slot which extends only partially through the interface between the support plate and the friction lining from one side thereof and opening through that side, and at least one other of the gripping elements and the associated slot also extends only partially through the interface from the other side thereof and opening through that side. The attachment according to claim 1 or 2, characterized in that at least one of the stop elements is a suitably shaped element received in a cavity that resides entirely within the friction lining material. The attachment according to any of the preceding claims, characterized in that the stop elements are attached to the support plate by means of screws, bolts or rivets that extend through openings in the support plate and towards the support plate. detention element. 6. The attachment according to claim 5, characterized in that the stop elements are also joined or cemented within the respective cavities. The attachment according to any of claims 1 to 5, characterized in that the stop elements are molded into the coating material during the molding of the shape of the coating material. The attachment according to any of the preceding claims, characterized in that a bonding agent between the coating material and the support plate is also provided. 9. An attachment between a friction lining material and a support plate, characterized in that it is substantially as described above with reference to Figures 1 to 5, or Figures 6 to 8, of the accompanying drawings. 10. The combination of a friction liner having at least one cavity and a stop element for association between them according to any of the preceding claims.