FRICTION PLATE HAVING MECHANICALLY CONNECTED FRICTION MATERIAL

A method of forming a friction plate is provided. The method includes force fitting a friction material onto a base to form a mechanical connection between the friction material and the base. A friction plate is also provided. The friction plate includes a base and a friction material force fit onto the base such that a mechanical connection is formed by a shape of the friction material and a shape of the base.

DETAILED DESCRIPTION

FIG. 1shows a portion of a friction plate10according to one exemplary embodiment of the present invention. Friction plate10includes a base12, here a steel ring, including a plurality of holes14formed therein. Friction material is provided in the embodiment shown inFIG. 1as a plurality of friction material plugs16. Plugs16matching the size and shape of holes14are inserted into each of the holes14. Steel ring12may be formed by punching holes14therein. Friction material plugs16may be formed by a separate punching operation, then inserted into holes14, or steel ring12may be used as a die block, with the friction material being pushed through holes14by a punch. Where steel ring12is used as a die block, a stamping die may be used to push all of plugs16through holes14at the same time or a “sewing machine” style operation may employed, where one or multiple plugs16may be pressed through holes at a time.

After plugs16are inside of holes14, friction plate10may be compressed between flat plates to calibrate the thickness and flatness of plugs16. The compression of plugs16causes the friction material of plugs16to expand outwardly towards the edges of holes14, further locking plugs16into holes14. The compression of plugs16causes the friction material to be force fit on steel ring12such that plugs16and steel ring12are mechanically connected by a shape of the friction material and a shape of the base. In a preferred embodiment, friction material16, after the compression, extends axially past steel ring12at least at the protrusions such that the friction material can contact adjacent separator plates400(FIG. 3) with without any contact between the separator plates400and steel ring12. In one preferred embodiment, steel ring12is approximately 0.8 mm thick and friction material plugs16are 1.4 mm thick after being compressed, with friction material plugs16protruding axially from both sides of steel ring12by 0.3 m. The axially protruding plugs16and a surface of steel ring12, which is recessed with respect to plugs16, form cooling grooves through which cooling oil may be passed. If the friction material has not been fully cured, friction plate10may then be heated to fully cure the friction material plugs16. In the embodiment shown inFIG. 1, two rows of plugs16, one row of first size and shape and another row of a second size and shape, are dispersed circumferentially throughout steel ring12. In other embodiments, more or less than two rows may be dispersed in steel ring12and plugs16may be of one or more sizes and shapes.

FIG. 2shows a portion of a friction plate110according to another exemplary embodiment of the present invention. Friction plate110includes a base112, here a steel ring, including a plurality of teeth114extending radially outward therefrom. Friction material is provided in the embodiment shown inFIG. 2as a friction material ring116positioned on the circumference of steel ring112. Friction material ring116includes a plurality of teeth118extending radially inward therefrom. Rings112,116are shaped such that teeth114interlock with teeth118to hold ring116in place on ring112, with teeth114matching the shape of spaces122formed between teeth118and teeth118matching the shape of spaces120formed between teeth114. In an alternative embodiment, steel ring112and friction material ring116may be in opposite positions, with friction material ring116having radially outward extending teeth and being on the inside of steel ring112, which is on the outside of friction material ring116and has radially inward extending teeth interlocking with the teeth of friction material ring116.

After friction material ring116is on steel ring112in an interlocking manner, friction material ring116may be compressed to form cooling grooves on the surface thereof. The compressing operation recesses portions of friction material ring, such that protrusions, similar to the pattern of plugs16shown inFIG. 1, extend above the recessed portions. Also, the friction material, even after compression, should extend axially past steel ring112at least at the protrusions. In one preferred embodiment, the friction material is compressed by approximately fifty percent at the recessed portions. The compressing operation may also strengthen the friction material, resulting in reinforcement against torsional and centrifugal loading. The compressing operation may also expand friction material ring116toward teeth114and spaces120of steel ring112, locking friction material ring116into place on steel ring112and forming a mechanical connection between steel ring112and friction material ring116. The compression of friction material ring116causes the friction material to be force fit on steel ring112such that friction material ring116and steel ring112are mechanically connected by a shape of the friction material and a shape of the base. Steel ring112and friction material ring116are thus joined together without adhesive bonding. After such a compressing operation is performed, an additional compressing operation may be performed, as similarly discussed above with respect to the embodiment inFIG. 1, with friction plate110being compressed between flat plates to calibrate the thickness and flatness of friction material ring116. This additional compressing operation may cause the friction material ring116to expand further toward teeth114and spaces122of steel ring112, further locking friction material ring116into place on steel ring112and strengthening the mechanical connection between friction material ring116and steel ring112. In a preferred embodiment, friction material ring116, after the one or more compressions, extends axially past steel ring112at least at the protrusions such that the friction material can contact adjacent separator plates400(FIG. 3) with without any contact between the separator plates400and steel ring112.

FIG. 3shows schematically a wet-type friction clutch50of a motor vehicle transmission having a plurality of friction plates100,200,300. Friction plates100,200,300may be formed in a similar manner as friction plate10as described inFIG. 1or friction plate110as described inFIG. 2. The axially-movable plates100,200,300can be pressed against axially-movable separator plates400by a piston52, for example a hydraulically-actuated piston, to provide frictional engagement.