CA1167758A - Method of making a ribbed belt - Google Patents
Method of making a ribbed beltInfo
- Publication number
- CA1167758A CA1167758A CA000364032A CA364032A CA1167758A CA 1167758 A CA1167758 A CA 1167758A CA 000364032 A CA000364032 A CA 000364032A CA 364032 A CA364032 A CA 364032A CA 1167758 A CA1167758 A CA 1167758A
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- CA
- Canada
- Prior art keywords
- belt
- cutters
- manufacture
- drive
- belt sleeve
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
ABSTRACT
A method of making a ribbed belt having a plurality of longitudinally extending ribs is provided, wherein a vulcanized belt sleeve is put into one man-drel or said belt sleeve laid over two mandrels and cut with a milling attachment combining multiple double angle milling cutters in such a manner that the rotation of the milling attachment is opposed to that of the mandrel and the revolution speed of the milling attach-ment is greater than that of the mandrel, thus precisely defining a ribbed section of the belt in a simultaneous manner.
A method of making a ribbed belt having a plurality of longitudinally extending ribs is provided, wherein a vulcanized belt sleeve is put into one man-drel or said belt sleeve laid over two mandrels and cut with a milling attachment combining multiple double angle milling cutters in such a manner that the rotation of the milling attachment is opposed to that of the mandrel and the revolution speed of the milling attach-ment is greater than that of the mandrel, thus precisely defining a ribbed section of the belt in a simultaneous manner.
Description
~ ~ 677~
Description METHOD OF MAKING A R]:BBED BELT
This invention relates to power transmission belt manufacture and more particularly to a method of making an endless power transmission ribbed belt. Such a ribbed belt is thin and flexible compared with ordi-nary V-belts, and is excellent in high-speed rotation and its ability to transmit power. Such ribbed belts are, therefore, widely used in drive devices of auto-mobiles wherein the power transmission belt is arranged in a serpentine path about the crank pulley, alternator pulley, a cooler pulley, etc.
A method (1) of forming a belt using a tubu-lar matrix is disclosed in U.S. Letters PatentsNos~
3,839,116 and 3,981,206. The method disclosed therein ~` comprises building up successively a lower fabric, a lower rubber layer, a tensile member, an upper rubber ~ layer, and an upper fabric, on a tubular matrix having `~ ~ a plurality of V-grooves in a circum~erential direction inserted into a~cylindrical drum, to form a vulcanized belt sleeve having a plurality of V~grooves. The belt ;~ sleeve is then cut into individual belts.
Another method (2) of forming a belt using a grinding wheel is disclosed in U.S. Letters Patents Nos.
3,818,576, 3,822,516 and 4,177,688, in which the vul-canized belt sleeve is formed on a mandrel and ground with a contoured grinding wheel to precisely define the desired plurality of longitudinally extending ribs.
Another method (3) of forming a belt is using a Rotocure mechanism as disclosed in U.S. Letters Patent - No. 4,139,406, in which a formed belt sleeve is laid ,'', ' :
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1 3 6775#
over the Rotocure mechanism having a plurality of V-grooves to define the desired ribbed section belt.
A casting method (4) of forming a belt is disclosed ln U.S. Letters Patent No. 3,813,197 and Great Britain Patent No. 1,123,225, which comprises the fixing of an inner mold having a fabric and a tensile member wound thereon, in an outer mold having a plural~
ity of V-grooves arranged circumferentially alony its inner surface, casting urethane elastomeric material in the mold cavity to form a belt sleeve, and cutting the belt sleeve into the desired final belts.
In carrying out methods (1), (2) and (3), the method using a grinding wheel (2) and the method using Rotocure (3), the ribbed belts may be made of an ordi-nary rubber, such as NR, SBR, CR, etc. I~n method (1),the use of a flat lower rubber layer on the tubular matrix is disadvantageous in that the tensile members may fall into the V-grooves of the tubular matrix durin~
vulcanization and thus become arranged randomly, which may result in an undesirable stretchable belt. However, the use of a ribbed lower rubber layer prevents such defects, and the manufacture of the belts is facilitated and improved. Another serious disadvantage in method (1) lies in the difficulty of removing the formed belt sleeve from the tubular matrix which conventionally causes a short lift of the tubular matrix.
In method (2), the surface temperature of the vulcanized belt sleeve reaches more than 100C. during the grinding process so that reversion, due to a break in the intermolecular bonds, occurs on the surface of the sleeve. This may produce troublesome sticky adhe-sion. Also, since the yieldable belt sleeve is deformed by the grinding wheel during the grinding operation, it is difficult to grind the V-grooves accurately. The .~
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material and roughne~s of the grinding wheel must be correlated with the hardness of the belt sleeve.
A problem arises in the method (3) manufacture in that the belt sleeve shrinks when it is removed from - 5 the heated Rotocure mechanism. The thermal efficiency of the process is therefore very low because the Roto-cure mechanism must be cooled before the belt sleeve is removed necessitating repeating hea~ing and cooling steps.
The above mentioned methods, which have been developed for making ribbed belts, have drawbacks con-cerning the accuracy o~ the V-grooves, ~ticky adhesion : o~ rubb`er in proportion to the generati~n of heat, dimensional instability after vulcanization, high cost, etc.
The prenent invention provlde~ an improved belt manufacture elimin~ti~ the disadvantagas of the background art method~ discu3s~d above 1~ a novel and simple mannar.
An object of the lnvention i~ to provide a method of making a ribbed belt in which th~ V-qrooves of the ribbed belt are accurat~ly formed.
Another object o~ the invention is to provide such a method of making a ribbed belt in which the cut-ting of the V-grooves i9 o~feoted in ~u~h a manner as ~o prevent ~ticky adh~sion of th~ vulcaniæed belt 31eeve.
In one broad aspect, tne invention per~ains to a method of manufacture of a drive belt having a series of parallel juxtaposed longitudinal tapered ribs, wherein a belt sleeve, having an elastomeric drive surface portion, is moved at a low rate of speed longitudinally ~hrough a cutting position. The method is characterized by urging concurrently a plurality of double angle V-shaped milling cutters into the drive surface portion of the moving belt sleeve while moving 35 the cutters concurrently in a direction opposite the move-ment of the belt sleeve, the speed of movement of the cutters .
being substantially greater than the speed of movement of the drive surface portion.
I :~ 6775 8 Thi~ invention will be deqcrib~d in detail with re~erence to the accompanying drawing~ wherein:
Figure 1 is a transv~rse section, with parts cut away, showing a ribbed belt formed by a manufactur-ing process embodying the invention;
. Figure 2 i~ a fragmentary section ~howing a first step in the method o fonming the vulcanized belt sleeve;
Figure 3 is a fragmentary sectional view illustrating the method of cutting the V-grooves in the sleeve`in one form o~ the invention;
Figure 4 i9 an elevation of a double angle mil-ling cutter tool for cutting the sleeve;
Figure 5 ~ a fragm~ntary ~ect~onal vlew taken along line 5-5 of Figure 4~
Figure 6 i8 a ~raqmentary ~ectional view illustrating the arrangement of the cu~ter tool at the completion of the cutting opsra~ion;
: ~igure 7 i~ a frag~entary ~ectional view illustrating the method of ~anu~acture o another exem-plary embodiment o~ a ribbe~ belt in a~cordaw e wit.h the invention;
. Figure 8 i~ a cro~s ~ection of a ribbed belt made by the method ~f ~igure 7; and Figure 9 is a side elevation ~howing a step in the method of manufacturing a long ribbed belt in : accordance with the invention.
-; Reference is now made to Fig. 1 of the draw-ing which illu9trates one exemplary embodiment of a ribbed belt, generally design~ted 1, manufactured by the improved pr~cess of the inventlon, Ribbed belt 1 is .~ .
.~ .
,.
`~ 35 I ~ ~77S~
made primarily of elastomeric material and comprises an upper rubber layer 2, a ropelike tensile member 3 rnade of, for instance, polyester fibers or aromatic poly-amide fibers high in strength and low in elongation, and a ribbed section 4 defined by a plurality of longi-tudinally extending V-grooves 5 and ribs 6 having a triangular cross section configuration. As shown, upper rubber layer 2 of belt 1 may be provided with an outer fabric cover layer 7.
Belt 1 is formed from a sleeve 8. The manu-facture~of sleeve 8 is illustrated in Fig. 2.
As shown, a stretchable fabric 9 is wound onto a cylindrical drum 10 in one or more plies.
Fabric 9 comprises a bias fabric having high stretch-- 15 ability, and may illustratively have warps and wefts forming a cross angle of 90 to 155 degrees. A lower rubber layer 11 is wound on the fabric 9. Thereafter, a ropelike tension member 12 made of, for instance, polyester fibers high in strength and low in elongation and covered with a cushioning rubber layer, is spirally wound onto lower rubber layer 11. The thickness of upper rubber layer 13 is preferably greater than that of lower rubber layer 11. Upper rubber layer 13 is laminated on the layer of the tensile member 12 and the assembly thus obtained is vulcanized in accordance with techniques well known in the art to form the completed belt sleeve 8.
The vulcanized belt sleeve is removed from the drum 10 and placed on an expandable mandrel 15.
The belt sleeve is then cut by means of a milling attachment 14. The rotating milling attachment 14 cuts the rotating belt sleeve 8 in a novel manner to provide an improved highly acaurate ribbed configuration.
~ s shown, belt sleeve 8 is placed on mandrel 15 so that upper rubber layer 13 defines the radially outer surface 31 of the belt sleeve. Prior to placing the belt sleeve on the mandrel, an expandable tubular member 16 may be mounted concentrically around the man-drel and preferably held in position by the frictional engagement of its inner surface with the outer surface o~ the mandrel. The expandable tubular member 16 is desirable in preventing damage to the cutter blades in the finishing process. Tubular member 16 illustra-tively may be formed of an inexpensive elastomeric material.
Mandrel 15 i5 then rotated in the indicated arrow direction by a suitable drive (not shown) con-nected to a drive shaft 17 of the mandrel.
Milling attachment 1~ includes a plurality ofdouble angle milling cutters 18 carried on a drive shaft generally designated 19, and a drive means 20 for driv-ing drive shaft 19 in an opposite direction of rotation as indicated by the arrow in Fig. 3. The number of double angle milling cutters 18 mounted on drive shaft 19 is determined by the number of V-grooves desired in the ribbed belt. The surface configuration of the mil-ling attachment comprises V-shaped protrusions 21 and V-shaped grooves 22 corresponding to the configuration of ribbed section 4 of belt 1.
Each double angle milling cutter 18, as shown in Figs. 4 and 5, is defined by a circular body section 33 and a plurality of cutting edges 30 regularly arranged about its circumference. The depth (d) of cutter edge 30 is almost equal to that of the ribs in the belt. Cutting edge 30, as shown, has a triangular cross section configuration. The double angle milling attachment 14 must be rotated in the direction desig-:` :
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1 1 ~7~5~
nated by an arrow, in such a manner that precise V-grooves are cut into the outer surface 31 of the belt sleeve 8.
By causing the attac~nent 14 and mandrel 15 to be rotated in opposite directions, it is possible to cut precise accurate V-grooves as a result of the double angle milling cutters pushing into the belt sleeve, while at the same time, the life of the cutting edge is effectively maximized.
In effecting the cutting of the V-grooves in the belt section 13, the rotating milling attachment 14 is slowly moved toward the rotating mandrel 15, namely, in the arrow direction (a) shown in Fig. 3, by a trans~
lating means 20 to urge the cutter into one end portion of the belt sleeve 8 whereupon the desired V-grooves are accurately cut into the outer surface 31 of the belt sleeve. In order to form the deslred triangular ribs 6, the double angle milling cutters 18 are pushed into the belt sleeve until the top of the V-shaped grooves 22 thereof are disposed at the outer surface 31 of the belt sleeve.
i The cutting speed of milling attachment 14 is preferably greater than the revolution speed of the sur-face 31 and preferably is from 30 to 130 times the sur-face speed in order to provide the V-grooves of the belt with a proper rough surface. At a ratio of less than approximately 30 to 1, the surfaces of the V-grooves are excessively rough, and the cutting step is inefficiently time consuming. On the other hand, at a ratio of more than 130 to 1, the V-groove surface of the belt is un-; desirably smooth so that the belt is liable to slip in use because of the coefficient of friction.
The desirable ratio of feed of milling attach-ment 14 rad:ally toward mandrel 15 is a function of the .
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hardness of the belt sleeve. More specifically, since each of the double angle milliny cutters 18 is con-currently engaging upper rubber layer 13 in the cutting operation, there is a tendency for upper rubber layer 13 to deform.
The upper and lower layers 13 and 16 may be made of a suitable elastomeric material, such as NR, SBR, rubber compound obtained by mixing short fibers in the above described rubber, polyurethane resin, etc.
The hardness (shore-A) of the elastomeric material is preferably from approximately 75 to 90. The feed velocity of milling attachment 1~ cutters into the belt sleeve outer layer is preferably approximately 2 to 10 mm/min.
If the feed velocity of the milling attachment is greater than 10 mm/min., it is difficult to cut the V-grooves precisely because of the resultant deformation of the belt sleeve. The milling attachment may be moved into the belt sleeve at a constant speed or inter-mittently, as desired.
Fig. 6 shows the arrangement of the apparatus at the end of the cutting step. The milling cutters have been urged deeply into the belt sleeve to a posi-tion near tensile member 12 whereby precise V-grooves ; 25 are cut into the outer layer of the belt sleeve.
The milling attachment 14 is then moved by translating means 20 away from mandrel 15 in the arrow direction (b) shown in Fig. 6, to space the cutters from the sleeve belt.
The milling attachment 1~ may now be moved by means 20 in the direction of the arrow (c), i.e., paral-lel to the drive shaft 17 into alignment with belt sleeve portion A to permit V-grooves to be cut in the portion A in a manner similar to that discussed above.
, ., .
~ ~ S7~58 As will be obvious to those skilled in the art! milling attachment 14 may be moved automatically in a preselected manner to provide the cut belt.
The belt sleeve haviny the plurality of V-grooves is then suitably cut into discrete annular ribbed belts by a conventional cutting machine, as well known in the art.
; Fig. 7 illustrates a modified method embodyiny the invention for manufacturing anotherexemplary embodi-ment of ribbed belt 23 illustrated in Fig. 8. Belt 23 is flat across the top 29 of the ribbed section 27.
Ribbed belt 23, as shown in Fig. 8, comprises an outer fabric layer 24, an upper rubber layer 25, a tensile member 26, and a ribbed section 27. Section 27 is defined by a plurality of longitudinally extending ribs 28 each having a trapezoidal cross section. It will be seen that the thickness of the upper rubber layer 13, `i shown in Fig. 7, may be a fraction, such as half of that of the upper rubber layer 13 shown in Figs. 3 and 6.
The double angle milling cutters la are urged ~ only partially into belt sleeve 8 so that the top 32 of ; ~ the V-shaped groove 22 remains spaced from outer sur-face 31 of belt sleeve 8. Resultingly, ribbed section 27 defines a trapezoidal cross section configuration.
The final manufacturing step in forminy the belt 23 may be carried out as described above relative to belt 1.
Fig. 9 shows a modified step in the manufac~
ture of a ribbed belt, advantageously adapted for use in making a long length ribbed belt. As shown, long belt sleeve 8 is entrained about both a driving mandrel 33 and a driven mandrel 34. The belt sleeve is stretched thereabout in order to prevent slip of the belt sleeve duriny the cutting operation. Driven mandrel 34 has flanges 35,36 on each side for preventing transverse -. ~
.
~ `
, , 1 1 6'~ ~58 shifting of the belt sleeve during the cutting step.
All other steps are similar to those described above.
Thus, in accordance with the disclosed inven-tion, the V-grooves of the ribbed belts are cut pre-cisely into the rib-forming section and have a pre-selected desired rough surface. The ribbed belts thusly manufactured have excellent power transmission characteristics and do not produce sticky adhesion as a result of generation of heat in use.
Thus, the method of belt manufacture of the present invention provides a significantly improved manufacture of such ribbed belts, overcoming the prior art problems incurred in the use of grinding wheels to form the belt grooves.
It is apparent that other modifications may be made without departing from the scope of this invention.
Description METHOD OF MAKING A R]:BBED BELT
This invention relates to power transmission belt manufacture and more particularly to a method of making an endless power transmission ribbed belt. Such a ribbed belt is thin and flexible compared with ordi-nary V-belts, and is excellent in high-speed rotation and its ability to transmit power. Such ribbed belts are, therefore, widely used in drive devices of auto-mobiles wherein the power transmission belt is arranged in a serpentine path about the crank pulley, alternator pulley, a cooler pulley, etc.
A method (1) of forming a belt using a tubu-lar matrix is disclosed in U.S. Letters PatentsNos~
3,839,116 and 3,981,206. The method disclosed therein ~` comprises building up successively a lower fabric, a lower rubber layer, a tensile member, an upper rubber ~ layer, and an upper fabric, on a tubular matrix having `~ ~ a plurality of V-grooves in a circum~erential direction inserted into a~cylindrical drum, to form a vulcanized belt sleeve having a plurality of V~grooves. The belt ;~ sleeve is then cut into individual belts.
Another method (2) of forming a belt using a grinding wheel is disclosed in U.S. Letters Patents Nos.
3,818,576, 3,822,516 and 4,177,688, in which the vul-canized belt sleeve is formed on a mandrel and ground with a contoured grinding wheel to precisely define the desired plurality of longitudinally extending ribs.
Another method (3) of forming a belt is using a Rotocure mechanism as disclosed in U.S. Letters Patent - No. 4,139,406, in which a formed belt sleeve is laid ,'', ' :
'~;
. ~ .
1 3 6775#
over the Rotocure mechanism having a plurality of V-grooves to define the desired ribbed section belt.
A casting method (4) of forming a belt is disclosed ln U.S. Letters Patent No. 3,813,197 and Great Britain Patent No. 1,123,225, which comprises the fixing of an inner mold having a fabric and a tensile member wound thereon, in an outer mold having a plural~
ity of V-grooves arranged circumferentially alony its inner surface, casting urethane elastomeric material in the mold cavity to form a belt sleeve, and cutting the belt sleeve into the desired final belts.
In carrying out methods (1), (2) and (3), the method using a grinding wheel (2) and the method using Rotocure (3), the ribbed belts may be made of an ordi-nary rubber, such as NR, SBR, CR, etc. I~n method (1),the use of a flat lower rubber layer on the tubular matrix is disadvantageous in that the tensile members may fall into the V-grooves of the tubular matrix durin~
vulcanization and thus become arranged randomly, which may result in an undesirable stretchable belt. However, the use of a ribbed lower rubber layer prevents such defects, and the manufacture of the belts is facilitated and improved. Another serious disadvantage in method (1) lies in the difficulty of removing the formed belt sleeve from the tubular matrix which conventionally causes a short lift of the tubular matrix.
In method (2), the surface temperature of the vulcanized belt sleeve reaches more than 100C. during the grinding process so that reversion, due to a break in the intermolecular bonds, occurs on the surface of the sleeve. This may produce troublesome sticky adhe-sion. Also, since the yieldable belt sleeve is deformed by the grinding wheel during the grinding operation, it is difficult to grind the V-grooves accurately. The .~
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' ~ ~6~5~
material and roughne~s of the grinding wheel must be correlated with the hardness of the belt sleeve.
A problem arises in the method (3) manufacture in that the belt sleeve shrinks when it is removed from - 5 the heated Rotocure mechanism. The thermal efficiency of the process is therefore very low because the Roto-cure mechanism must be cooled before the belt sleeve is removed necessitating repeating hea~ing and cooling steps.
The above mentioned methods, which have been developed for making ribbed belts, have drawbacks con-cerning the accuracy o~ the V-grooves, ~ticky adhesion : o~ rubb`er in proportion to the generati~n of heat, dimensional instability after vulcanization, high cost, etc.
The prenent invention provlde~ an improved belt manufacture elimin~ti~ the disadvantagas of the background art method~ discu3s~d above 1~ a novel and simple mannar.
An object of the lnvention i~ to provide a method of making a ribbed belt in which th~ V-qrooves of the ribbed belt are accurat~ly formed.
Another object o~ the invention is to provide such a method of making a ribbed belt in which the cut-ting of the V-grooves i9 o~feoted in ~u~h a manner as ~o prevent ~ticky adh~sion of th~ vulcaniæed belt 31eeve.
In one broad aspect, tne invention per~ains to a method of manufacture of a drive belt having a series of parallel juxtaposed longitudinal tapered ribs, wherein a belt sleeve, having an elastomeric drive surface portion, is moved at a low rate of speed longitudinally ~hrough a cutting position. The method is characterized by urging concurrently a plurality of double angle V-shaped milling cutters into the drive surface portion of the moving belt sleeve while moving 35 the cutters concurrently in a direction opposite the move-ment of the belt sleeve, the speed of movement of the cutters .
being substantially greater than the speed of movement of the drive surface portion.
I :~ 6775 8 Thi~ invention will be deqcrib~d in detail with re~erence to the accompanying drawing~ wherein:
Figure 1 is a transv~rse section, with parts cut away, showing a ribbed belt formed by a manufactur-ing process embodying the invention;
. Figure 2 i~ a fragmentary section ~howing a first step in the method o fonming the vulcanized belt sleeve;
Figure 3 is a fragmentary sectional view illustrating the method of cutting the V-grooves in the sleeve`in one form o~ the invention;
Figure 4 i9 an elevation of a double angle mil-ling cutter tool for cutting the sleeve;
Figure 5 ~ a fragm~ntary ~ect~onal vlew taken along line 5-5 of Figure 4~
Figure 6 i8 a ~raqmentary ~ectional view illustrating the arrangement of the cu~ter tool at the completion of the cutting opsra~ion;
: ~igure 7 i~ a frag~entary ~ectional view illustrating the method of ~anu~acture o another exem-plary embodiment o~ a ribbe~ belt in a~cordaw e wit.h the invention;
. Figure 8 i~ a cro~s ~ection of a ribbed belt made by the method ~f ~igure 7; and Figure 9 is a side elevation ~howing a step in the method of manufacturing a long ribbed belt in : accordance with the invention.
-; Reference is now made to Fig. 1 of the draw-ing which illu9trates one exemplary embodiment of a ribbed belt, generally design~ted 1, manufactured by the improved pr~cess of the inventlon, Ribbed belt 1 is .~ .
.~ .
,.
`~ 35 I ~ ~77S~
made primarily of elastomeric material and comprises an upper rubber layer 2, a ropelike tensile member 3 rnade of, for instance, polyester fibers or aromatic poly-amide fibers high in strength and low in elongation, and a ribbed section 4 defined by a plurality of longi-tudinally extending V-grooves 5 and ribs 6 having a triangular cross section configuration. As shown, upper rubber layer 2 of belt 1 may be provided with an outer fabric cover layer 7.
Belt 1 is formed from a sleeve 8. The manu-facture~of sleeve 8 is illustrated in Fig. 2.
As shown, a stretchable fabric 9 is wound onto a cylindrical drum 10 in one or more plies.
Fabric 9 comprises a bias fabric having high stretch-- 15 ability, and may illustratively have warps and wefts forming a cross angle of 90 to 155 degrees. A lower rubber layer 11 is wound on the fabric 9. Thereafter, a ropelike tension member 12 made of, for instance, polyester fibers high in strength and low in elongation and covered with a cushioning rubber layer, is spirally wound onto lower rubber layer 11. The thickness of upper rubber layer 13 is preferably greater than that of lower rubber layer 11. Upper rubber layer 13 is laminated on the layer of the tensile member 12 and the assembly thus obtained is vulcanized in accordance with techniques well known in the art to form the completed belt sleeve 8.
The vulcanized belt sleeve is removed from the drum 10 and placed on an expandable mandrel 15.
The belt sleeve is then cut by means of a milling attachment 14. The rotating milling attachment 14 cuts the rotating belt sleeve 8 in a novel manner to provide an improved highly acaurate ribbed configuration.
~ s shown, belt sleeve 8 is placed on mandrel 15 so that upper rubber layer 13 defines the radially outer surface 31 of the belt sleeve. Prior to placing the belt sleeve on the mandrel, an expandable tubular member 16 may be mounted concentrically around the man-drel and preferably held in position by the frictional engagement of its inner surface with the outer surface o~ the mandrel. The expandable tubular member 16 is desirable in preventing damage to the cutter blades in the finishing process. Tubular member 16 illustra-tively may be formed of an inexpensive elastomeric material.
Mandrel 15 i5 then rotated in the indicated arrow direction by a suitable drive (not shown) con-nected to a drive shaft 17 of the mandrel.
Milling attachment 1~ includes a plurality ofdouble angle milling cutters 18 carried on a drive shaft generally designated 19, and a drive means 20 for driv-ing drive shaft 19 in an opposite direction of rotation as indicated by the arrow in Fig. 3. The number of double angle milling cutters 18 mounted on drive shaft 19 is determined by the number of V-grooves desired in the ribbed belt. The surface configuration of the mil-ling attachment comprises V-shaped protrusions 21 and V-shaped grooves 22 corresponding to the configuration of ribbed section 4 of belt 1.
Each double angle milling cutter 18, as shown in Figs. 4 and 5, is defined by a circular body section 33 and a plurality of cutting edges 30 regularly arranged about its circumference. The depth (d) of cutter edge 30 is almost equal to that of the ribs in the belt. Cutting edge 30, as shown, has a triangular cross section configuration. The double angle milling attachment 14 must be rotated in the direction desig-:` :
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1 1 ~7~5~
nated by an arrow, in such a manner that precise V-grooves are cut into the outer surface 31 of the belt sleeve 8.
By causing the attac~nent 14 and mandrel 15 to be rotated in opposite directions, it is possible to cut precise accurate V-grooves as a result of the double angle milling cutters pushing into the belt sleeve, while at the same time, the life of the cutting edge is effectively maximized.
In effecting the cutting of the V-grooves in the belt section 13, the rotating milling attachment 14 is slowly moved toward the rotating mandrel 15, namely, in the arrow direction (a) shown in Fig. 3, by a trans~
lating means 20 to urge the cutter into one end portion of the belt sleeve 8 whereupon the desired V-grooves are accurately cut into the outer surface 31 of the belt sleeve. In order to form the deslred triangular ribs 6, the double angle milling cutters 18 are pushed into the belt sleeve until the top of the V-shaped grooves 22 thereof are disposed at the outer surface 31 of the belt sleeve.
i The cutting speed of milling attachment 14 is preferably greater than the revolution speed of the sur-face 31 and preferably is from 30 to 130 times the sur-face speed in order to provide the V-grooves of the belt with a proper rough surface. At a ratio of less than approximately 30 to 1, the surfaces of the V-grooves are excessively rough, and the cutting step is inefficiently time consuming. On the other hand, at a ratio of more than 130 to 1, the V-groove surface of the belt is un-; desirably smooth so that the belt is liable to slip in use because of the coefficient of friction.
The desirable ratio of feed of milling attach-ment 14 rad:ally toward mandrel 15 is a function of the .
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hardness of the belt sleeve. More specifically, since each of the double angle milliny cutters 18 is con-currently engaging upper rubber layer 13 in the cutting operation, there is a tendency for upper rubber layer 13 to deform.
The upper and lower layers 13 and 16 may be made of a suitable elastomeric material, such as NR, SBR, rubber compound obtained by mixing short fibers in the above described rubber, polyurethane resin, etc.
The hardness (shore-A) of the elastomeric material is preferably from approximately 75 to 90. The feed velocity of milling attachment 1~ cutters into the belt sleeve outer layer is preferably approximately 2 to 10 mm/min.
If the feed velocity of the milling attachment is greater than 10 mm/min., it is difficult to cut the V-grooves precisely because of the resultant deformation of the belt sleeve. The milling attachment may be moved into the belt sleeve at a constant speed or inter-mittently, as desired.
Fig. 6 shows the arrangement of the apparatus at the end of the cutting step. The milling cutters have been urged deeply into the belt sleeve to a posi-tion near tensile member 12 whereby precise V-grooves ; 25 are cut into the outer layer of the belt sleeve.
The milling attachment 14 is then moved by translating means 20 away from mandrel 15 in the arrow direction (b) shown in Fig. 6, to space the cutters from the sleeve belt.
The milling attachment 1~ may now be moved by means 20 in the direction of the arrow (c), i.e., paral-lel to the drive shaft 17 into alignment with belt sleeve portion A to permit V-grooves to be cut in the portion A in a manner similar to that discussed above.
, ., .
~ ~ S7~58 As will be obvious to those skilled in the art! milling attachment 14 may be moved automatically in a preselected manner to provide the cut belt.
The belt sleeve haviny the plurality of V-grooves is then suitably cut into discrete annular ribbed belts by a conventional cutting machine, as well known in the art.
; Fig. 7 illustrates a modified method embodyiny the invention for manufacturing anotherexemplary embodi-ment of ribbed belt 23 illustrated in Fig. 8. Belt 23 is flat across the top 29 of the ribbed section 27.
Ribbed belt 23, as shown in Fig. 8, comprises an outer fabric layer 24, an upper rubber layer 25, a tensile member 26, and a ribbed section 27. Section 27 is defined by a plurality of longitudinally extending ribs 28 each having a trapezoidal cross section. It will be seen that the thickness of the upper rubber layer 13, `i shown in Fig. 7, may be a fraction, such as half of that of the upper rubber layer 13 shown in Figs. 3 and 6.
The double angle milling cutters la are urged ~ only partially into belt sleeve 8 so that the top 32 of ; ~ the V-shaped groove 22 remains spaced from outer sur-face 31 of belt sleeve 8. Resultingly, ribbed section 27 defines a trapezoidal cross section configuration.
The final manufacturing step in forminy the belt 23 may be carried out as described above relative to belt 1.
Fig. 9 shows a modified step in the manufac~
ture of a ribbed belt, advantageously adapted for use in making a long length ribbed belt. As shown, long belt sleeve 8 is entrained about both a driving mandrel 33 and a driven mandrel 34. The belt sleeve is stretched thereabout in order to prevent slip of the belt sleeve duriny the cutting operation. Driven mandrel 34 has flanges 35,36 on each side for preventing transverse -. ~
.
~ `
, , 1 1 6'~ ~58 shifting of the belt sleeve during the cutting step.
All other steps are similar to those described above.
Thus, in accordance with the disclosed inven-tion, the V-grooves of the ribbed belts are cut pre-cisely into the rib-forming section and have a pre-selected desired rough surface. The ribbed belts thusly manufactured have excellent power transmission characteristics and do not produce sticky adhesion as a result of generation of heat in use.
Thus, the method of belt manufacture of the present invention provides a significantly improved manufacture of such ribbed belts, overcoming the prior art problems incurred in the use of grinding wheels to form the belt grooves.
It is apparent that other modifications may be made without departing from the scope of this invention.
Claims (10)
1. A method of manufacture of a drive belt having a series of parallel juxtaposed longitudinal tapered ribs wherein a belt sleeve having an elastomeric drive surface portion is moved at a low rate of speed longitudinally through a cutting position, characterized by urging concurrently a plurality of double angle V-shaped milling cutters into the drive surface portion of the moving belt sleeve while moving the cutters concurrently in a direction opposite the movement of the belt sleeve, the speed of movement of the cutters being substantially greater than the speed of movement of the drive surface portion.
2. The method of manufacture of a drive belt of Claim 1 wherein the speed of movement of the cutters is in the range of 30 to 130 times the speed of movement of the drive surface portion.
3. The method of manufacture of a drive belt of Claim 1 wherein the speed of movement of the cutters is in the range of 30 to 130 times the speed of movement of the drive surface portion and said cutters are urged into the drive surface portion at a rate of approximately 2 to 10 millimeters per minute.
4. The method of manufacture of a drive belt of Claim 1 wherein the width of the belt sleeve is at least twice that of the plurality of cutters and the manufacture further includes removing the cutters from engagement with the belt sleeve upon completion of the formation of a first group of ribs and causing the plurality of cutters to form a second group of ribs adjacent the first group.
5. The method of manufacture of a drive belt of Claim 1 wherein said cutters are urged fully into said drive surface portion to define triangular ribs.
6. The method of manufacture of a drive belt of Claim 1 wherein said cutters are urged less than fully into said drive surface portion to define trapezoidal ribs.
7. The method of manufacture of a drive belt of Claim 1 wherein the direction of rotation of the milling attachment is opposed to the direction of rotation of said belt sleeve.
8. The method of manufacture of a drive belt of Claim 1 wherein the belt sleeve is placed on a mandrel and an expandable tubular member extends concentrically about said mandrel and is held in position thereon by frictional engagement of its inner surface with the outer surface of said mandrel, prior to placing said belt sleeve about said mandrel.
9. The method of manufacture of a drive belt of Claim 1 wherein said cutters are fed into said belt sleeve until the tops of the V-shaped grooves between the cutters are in a preselected spaced relationship to the outer surface of the belt sleeve to form a ribbed section having a substantially trapezoidal cross section configuration.
10. The method of manufacture of a drive belt of Claim 1 wherein said belt sleeve encircles a driving mandrel and a driven mandrel, and said cutters engage said belt sleeve at said driven mandrel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000364032A CA1167758A (en) | 1980-11-05 | 1980-11-05 | Method of making a ribbed belt |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000364032A CA1167758A (en) | 1980-11-05 | 1980-11-05 | Method of making a ribbed belt |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1167758A true CA1167758A (en) | 1984-05-22 |
Family
ID=4118345
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000364032A Expired CA1167758A (en) | 1980-11-05 | 1980-11-05 | Method of making a ribbed belt |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1167758A (en) |
-
1980
- 1980-11-05 CA CA000364032A patent/CA1167758A/en not_active Expired
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| Date | Code | Title | Description |
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| MKEX | Expiry |