Metal deforming – With cutting – By composite tool
Reexamination Certificate
2001-10-31
2004-06-01
Crane, Daniel C. (Department: 3725)
Metal deforming
With cutting
By composite tool
C072S412000, C072S331000
Reexamination Certificate
active
06742373
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a manufacturing method of a V-block for a metal belt type continuously variable transmission in which press forming is easy and durability of press die is high.
BACKGROUND ART
There has been known a metal belt type continuously variable transmission having an endless metal belt comprising a thin metal ring assembly formed by thin metal rings piled on each other stratified and many V-blocks supported by the thin metal ring assembly along its circumference. The endless metal belt is wound round a drive pulley and a driven pulley and speed change ratio is controlled by changing widths of grooves of the pulleys. The V-block has a shape as shown in
FIGS. 14
,
15
(
FIGS. 2
a
,
2
b
of Japanese Laid-Open Patent Publication Hei 2-225840). Hitherto, the V-block was manufactured in the manner as follows. A plate material of an uniform thickness is punched in a front shape of the V-block to obtain the V-block, and at that time, while thickness of an outer portion of the V-block is left at the uniform thickness, an inner portion of the V-block is press-crushed so that the thickness is reduced gradually toward the innermost portion from a rocking edge.
In order to reduce volume to be press-crushed, as shown in
FIGS. 16
,
17
, the inner portion of the V-block is formed thin stepwise in advance, then a slant surface extending from the rocking edge toward the inner portion is formed by a counter punch.
If a V-block as shown in
FIGS. 14
,
15
is manufactured without changing thickness of the plate material partly, since mean depth of the press-crushing at the inner portion of the V-block is large, abrasion of a die is severe to shorten the life of the die and result in high cost.
In the V-block shown in
FIGS. 16
,
17
having the center of gravity positioned outside of the rocking edge, since a large deformation is given only a portion between the step portion and the rocking edge, press-crushed volume is small. However, the inner portion to be subjected to a strong compressive force by a surface of a V-groove of the pulley is thin so that strength and rigidity of the inner portion is insufficient, side surface of the inner portion contacted with the V-groove of the pulley is deformed to be worn severely, loads allotted to the V-block and the metal ring become unequal by deformation of the saddle surface, and lowering of durability of the metal belt and power transmitting efficiency is inevitable.
Further, in the prior art shown in
FIGS. 16
,
17
, since depth of the press-crushing becomes deeper from an outer side toward an inner side unilaterally, press reaction force of a main punch and a counter punch acts in an outer direction, gaps between the die and the main punch and between the die and the counter punch become not constant to be widened partly, shape accuracy of the V-block is lowered, or a broken surface which is not a shear surface is produced at a portion.
DISCLOSURE OF INVENTION
In order to overcome the above-mentioned difficulties, the present invention provides a method for manufacturing a V-block of a metal belt type continuously variable transmission having an endless metal belt comprising a thin metal ring assembly formed by thin metal rings piled on each other stratified and many V-blocks supported by the thin metal ring assembly along its circumference, and wound round a drive pulley and a driven pulley for controlling speed change ratio by changing widths of grooves of the pulleys, wherein the V-block is formed by punching a V-belt press material with a main punch and a counter punch; the V-block press material has a section including an outer portion of about uniform width and a tapered inner portion having a slant gently inclined toward an innermost end of the material from a place distant from a rocking edge by a predetermined distance inward; the main punch and the counter punch have front shapes of the substantially same as that of the V-block; and either punch facing the rocking edge has a slant starting at a place corresponding to the rocking edge and extending inward rising gradually.
According to this invention, the press-crushed part of the V-block press material is thickest at the beginning point of the taper of the V-block press material and becomes gradually thinner from the beginning point toward the rocking edge, as well as similarly becoming gradually thinner from the beginning point inward. Therefore, mean crushing depth of the press-crushed part of the V-block press material becomes smaller than that of the customary method in which the crushed part becomes gradually thicker from the rocking edge inward. As the result, local surface pressure of the counter punch on press forming can be made low to greatly prolong the life of the press die.
Further, according to the invention, since thickness of the inner portion of the V-block does not reduced remarkably compared with thickness of the outer portion, strength and rigidity of the inner portion, which is subjected to strong compressive load by the V-groove of the pulley, is not lowered so largely, so that abrasion of a part of the V-block contacted with the pulley is small, loads allotted to the V-block and the metal ring hardly become unequal by deformation of the saddle surface, and durability of the metal belt and power transmitting efficiency are improved.
If press-crush volume at a portion between the beginning point of the taper and the rocking edge of the V-block press material and press-crush volume at a region inside of the beginning point of the taper of the V-block press material are substantially equal, almost no press reaction force accompanying press forming acts on the punch, relative position of the punch with respect to the die can be maintained exactly, accuracy of shape and size can be improved greatly and no broken surface is produced.
According to another aspect of the present invention, there is provided a die for manufacturing a V-block of a metal belt type continuously variable transmission, wherein the die has a front shape of the substantially same as that of the V-block; the die comprises a main punch and a counter punch having parallel surfaces for pinching a V-block press material having a sectional view including an outer portion of about uniform width and a tapered inner portion having a slant gently inclined toward an innermost end of the material from a place distant from a rocking edge by a predetermined distant inward; and either punch of the main and counter punches facing the rocking edge has a slant starting at a place corresponding to the rocking edge and extending inward rising gradually.
REFERENCES:
patent: 4320647 (1982-03-01), Kummeling et al.
patent: 6427512 (2002-08-01), Suzuki et al.
patent: 6453716 (2002-09-01), Suzuki
patent: 0 278 545 (1988-08-01), None
patent: 63-115638 (1988-05-01), None
patent: 63-277703 (1988-11-01), None
patent: 02-225840 (1990-07-01), None
patent: 8-10882 (1996-01-01), None
patent: 2001-21007 (2001-01-01), None
Arent & Fox PLLC
Crane Daniel C.
Honda Giken Kogyo Kabushiki Kaisha
LandOfFree
Method for manufacturing a V-block of a metal belt type... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for manufacturing a V-block of a metal belt type..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for manufacturing a V-block of a metal belt type... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3341165