CA1082114A

CA1082114A - Disc brake pad and method of making a backing plate therefor

Info

Publication number: CA1082114A
Application number: CA295,209A
Authority: CA
Inventors: Simon Arbesman; Roman Arbesman; Albert Bachli
Original assignee: Royal Industries Inc
Current assignee: Royal Industries Inc
Priority date: 1978-01-18
Filing date: 1978-01-18
Publication date: 1980-07-22
Also published as: FR2415239A1; DE2822900A1; JPS5498463A; GB2012647B; GB2012647A; IT1111175B; IT7822767A0

Abstract

ABSTRACT OF THE DISCLOSURE
A disc brake pad including a relatively thick backing plate with bore holes preformed therethrough at selected locations; extrusion pressures being applied to a surface of the baking plate around each such bore hole to form a recess terminating within the baking plate at a narrow shoulder around the bore hole and also to extrude the backing plate material around a pilot pin in the bore hole to form a hollow rivet projecting from the opposite surface of the backing plate by which the pad of friction material is attached thereto in the disc brake pad.

Description

10~;~114 FIELD OF THE INVENTION
The present invention relates to an improved disc brake pad having a backing plate formed with at least one hollow rivet integral with and projecting from said backing plate and relates, as well, to a method of equipping metal plate intended or suitable for use in disc brake pads with such rivets by which brake lining may be secured to the metal plate to fabricate the improved braXe pad.
~ACKGROUND OF THE INVENTION
While it is already known to provide sheet or thin plate with integrally formed rivets which project from one face of such a plate to enable such plate to be secured by - such rivets to another metal plate, Applicant is unaware of any prior suggestion for providing integral rivets in thick 1~ plates as used in the manufacture of brake pads for vehicles.
Additionally, the known manner of integrally forming rivets in a metal plate has presented certain practical disadvantages contra-indicating its application to the manufacture of vehicle brake pads.
In the conventional procedure for the manufacture of such vehicle brake pads, it is common to utilize separate rivets which extend partially through both the backing plate and the friction brake lining, such rivets having beads which engage annular seatings within bores in the friction

2~ brake lining and being outwardly staked over annular shoulders within recesses provided for such purpose in the ~ -backing plate.
During the use of such brake pads, the large shear stresses experienced by the friction material layer have been known to work loose the separate rivets in the brake pad ~k 10~

and thus ultimately hasten the deterioration and destruction of its friction material lining.
It is accordingly a principal object of this invention to provide not only a novel method for forming an integral hollow rivet on a metal disc brake backing plate, but also an improved disc brake pad with a backing plate produced by such method.
More particularly and in accordance with a preferred feature of this invention, it is an object thereof to provide a said metal plate with at least one such integrally formed rivet and which plate can advantageously be utilized as a backing plate for a vehicle brake pad and especially as a disc brake pad where the problem of failure arising from shear stresses is of considerable importance.
Other objects of the inventio~ will become apparent as the description herein proceeds.
SUMMARY OF THE INVENTION !
Broadly, the invention provides a method of forming an integral hollow rivet on a metal plate as aforesaid which comprises extruding some of the metal about a bore through the plate in the form of an open-ended hollow rivet projecting from one surface of said plate and terminally defined by an annular shoulder within a recess extending into the plate from the other surface thereof and simultaneously formed in said plate.
Normally, the rivet and the recess including the annular shoulder terminally defining such a rivet will both have right cylindrical configurations and will be co-axial.
In accordance with an optional but preferred feature 108~1~4 of this invention, the aforementioned annular shoulder will be disposed nearer to one surface of the metal plate, i.e. the one from which the rivet projects, than to the other or opposite surface of the plate.
Additionally, it is preferred that the rivet have an external diameter which is smaller than the internal diameter of the recess including the annular shoulder terminally defining the rivet.
The described method is particularly practiced on metal plate, suitable for use in backing plates for disc brake pads, in order to equip the metal plate with hollow rivets as described by which a pad of friction material or brake lining may be secured to a suitably contoured metal plate in the fabrication of an improved disc brake pad.
It'will be understood and appreciated that metal plate suitable for use in backing plates for disc brake pads are necessarily sturdy --- hence, thick.
In addition, the metal plate must also be capable of being sheared, punched and otherwise pressed to contour and perforated as required.
The invention capitalizes both on the thickness and malleability of the plate by using it as the source metal from which the present rivets are extruded in the manner taught.
Other features of the invention and the advantages presented thereby will become apparent as the description herein proceeds.
BRIEF DESCRIPTION OF THE DRAWJ~GS
The invention will now be described merely by way of illustration with reference to the accompanying drawings 222 P/8 CA _ 3 _ ~O~Z114 in which: -Fig. 1 - is an isometric view of a fragment of a metal plate having a rivet integrally formed therewith in accordance with the invention;
Fig. 2 - is a section along line 2-2 of Fig. l;
Fig. 3 - is a somewhat schematic sectional illustration of the metal plate in position for and prior to the forming of such a rivet;
Fig. 4 - is a somewhat schematic sectional illustration showing the first step in forming the rivet; -Fig. 5 - is a perspective view of a disc brake pad constructed in accordance with the teaching of-this invention;
Fig. 6 - is a somewhat schematic sectional illustratlon showing the staking of the rivet over a layer of brake pad friction material, and Fig. 7 - is a fragmentary sectional view on a relatively large scale through the brake -pad shown in Fig. 5 when taken as indicated by the arrows 7-7 of that figure and showing details of one of the rivets by which the brake pad friction material is secured to the backing plate. ~ -~

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222 P/8 CA - 4 ~ -:, ' ' ", ~ ~' '`"'' :

~08'~114 Reference will first be made to Fig. 1 in which there is shown a fragment of a metal plate 10 integrally formed with a rivet generally indicated at 12 in accordance with this invention.
The rivet 12 is open-ended and hollow and has a right cylindrical wall 13 projecting transversely from one surface 14 of plate 10. The rivet 12 is terminally defined by an annular shoulder 20 within a cylindrical recess 22 extending into the plate 10 from its other surface 16. The recess 22, which is essentially co-axial with the rivet 12, has an internal diameter which is usefully slightly larger ~-than the external diameter of the rivet 12.
In accordance with another preferred feature of this inventionj the annular shoulder 20 is positioned so as to be nearer to the surface 14 of the plate 10 than it is to the surface 16 of that plate; the depth of recess 22 representing a ma~or part of the total thickness of the plate 10.
While the plate fragment 10 is shown in Fig. 1 as 20 having only one rivet 12 formed thereon, it will be under-stood that more than one such rivet can be provided on a full size plate as used for example in the brake pad of Fig. 5.
Referring now to Fig. 5, it will be seen that there is shown therein generally at 24 an automotive disc brake pad comprising a backing plate generally indicated at 26 having a pad or layer of friction material generally indicated at 28 secured on its uppermost surface 14 by five rivets of which only one is shown in Fig's. 6 and 7. It will 30 now be understood that the backing plates 26 shown in Fig's. 5 ~0~114 6 and 7 correspond to the plate fragment 10 shown in Fig. 1 for example, and consequently the same legends are used in all four figures to identify the corresponding items.
Since the rivet 12 is shown in Fig. 7 as having been staked and consequently somewhat deformed, it is, therefore, indicated generally in that figure by the legend 30.
From Fig. 7, it will be seen that the rivet 30 is outwardly staked over an annular seating 32 formed for such purpose in a bore 34 formed in the friction material layer 28.
As already indicated, one of the principal advantages provided by the present invention is improved resistance to movement of the friction material layer 28 relative to the backing plate 26 under the high shear stresses applied to such a brake pad in use. This improved resistance to such movement results from the structure of the rivet 30 and particularly from the fact that it is integrally formed with the backing plate 26; making it impossible for the rivet 10 (or 30) to work loose in backing plate 10 (or 26).
In Fig. 3 the plate 10 is seen to be equipped with 20 a pilot hole 40 formed therein by any means, and is shown ~ -in Fig. 4 as supported on an anvil die 44 with a cylindrical die hole 46 arranged in co-axial registration with pilot hole 40. Punch 48 also shown in this view has a locating pin 50 co-dimensional with and receivable in the pilot hole 40 to preserve centrality; the main body 52 of the punch 48 rearward of the locating pin 50 having a larger diameter.
As will be observed, plate 10 has been inverted in Fig's. 3 and 4 to assume the position normally occupied *hereby in the punching phase.

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108~114 It will be noted that the diameter of the die hole 46 is greater than that of the locating pin 50 to provide a narrow annular space therebetween but it is preferably slightly less than that of the main body 52 of the punch 5 48.
On extrusion stroke of the punch 48, the annular edge 54 of its main body g2 engages a narrow rim 55 of the material of the plate 10 and effectively and transversely extrudes it into the space between the wall of the die hole 10 46 and the locating pin 50 as shown in Fig. 4, so as to form the rivet wall 13. Simultaneously, the recess 22 and shoulder 20 are formed in the plate!10.
On completion of this punching/extruding operation, there is obtained the product shown in Fig. 1. It should lg perhaps be stressed at this juncture that the initial punching of the bore 40 in the plate 10, or the forming of such bore in any other manner, for example, by drilling, is an essential step in the method provided by this invention.
Finally, reference will be made to Fig. 6 which shows 20 somewhat schematically the staking of the rivet 12 to secure the friction material layer 28 to the backing plate 26. As already explained, the former is provided with counterbore 34 having an internal seating 32. During such staking ~-operation, an anvil post 56 is inserted into the recess 22 2g so as to engage the shoulder 20. A punch 58 having a chamfered nose is driven in the bore 34 against the upper end of the rivet wall 13 to stake that rivet over the seating 32; Fig. 6 showing such staking partially effected. Continued -downward movement of the staking punch produces the result 30 shown in Fig. 7.

222 P/8 CA _ 7 _ ... . . .

10~3Z~14 While the invention has hereinbefore been specifically described with reference to the embodiments thereof as shown in the accompanying drawings, it should be understood that variations in and modifications of the 5 described structure and procedure are possible within the sco-e of this invention.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS: -

1. Method of equipping metal plate, suitable for use in backing plates for brake pads, with at least one hollow rivet integral with and projecting from a surface of said metal plate comprising, preforming a bore through said metal plate; applying extrusion pressures to a surface of said plate around said bore to form a recess terminating within said plate at a narrow shoulder surrounding said bore and simultaneously to extrude metal from said backing plate in the form of a hollow rivet projecting from the opposite surface of said plate.

2. Method as set forth in Claim 1 in which said rivet is extruded around a pilot pin located in said bore.

3. Method as set forth in Claim 2 wherein said rivet is extruded into a die bore to which said rivet corresponds in transverse dimensions and contours.

4. Method as set forth in Claim 3 in which said recess extends more than half-way into but not through the thickness of said metal plate.

5. Method as set forth in Claim 1 in which said bore, recess and rivet are essentially cylindrical and co-axial.

6. Method as set forth in Claim 5 in which said metal is shaped as a backing plate and has a plurality of said integral hollow rivets formed thereon and projecting from one surface thereof.

7. A disc brake pad comprising a backing plate and a conforming pad of friction material centered on and secured to said backing plate by rivets; at least one of said rivets being a hollow rivet integral with and extruded from said backing plate.

8. A disc brake pad as set forth in Claim 7 in which the friction material is provided with recessed annular seatings;
said extruded rivet being staked over a said annular seating.

9. Method as set forth in Claim 1 wherein the extruded rivet is elongated to a length sufficient to enable it to extend into a bore of a disc brake pad and to be staked over a shoulder formed within said bore to secure said pad to said backing plate.