CA1222889A - Method of pulley manufacture and product - Google Patents
Method of pulley manufacture and productInfo
- Publication number
- CA1222889A CA1222889A CA000402458A CA402458A CA1222889A CA 1222889 A CA1222889 A CA 1222889A CA 000402458 A CA000402458 A CA 000402458A CA 402458 A CA402458 A CA 402458A CA 1222889 A CA1222889 A CA 1222889A
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- pulley
- wall portion
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- wall
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Abstract
ABSTRACT OF THE DISCLOSURE
This invention relates to a novel method of making pulleys and pulley blanks from sheet metal. The sheet metal is stamped into pulley blanks having an upstanding cylindrical wall, the cylindrical wall is then thickened by being partially collapsed axially, followed by contacting with a roller. The roller can have a plurality of v-shaped grooves on its surface, to form a pulley for use with a poly-v belt. The pulley is provided during manufacture with flanges which strengthen it.
This invention relates to a novel method of making pulleys and pulley blanks from sheet metal. The sheet metal is stamped into pulley blanks having an upstanding cylindrical wall, the cylindrical wall is then thickened by being partially collapsed axially, followed by contacting with a roller. The roller can have a plurality of v-shaped grooves on its surface, to form a pulley for use with a poly-v belt. The pulley is provided during manufacture with flanges which strengthen it.
Description
Z~2~38~
MET~IOD OF PULLEY MANUFACTURE AND PRODUCT
This application relates to a method of thickening sheet metal in selected areas. In a more preferred embodiment, this application relates to a method of making pulleys from sheet metal.
The method of making pulleys from sheet metal has long been known. Such pulleys are often made by a metal spinning process, such as that shown in Wickwire et al, U.S.P. 2,685,856, dated August 10, 1954, or Harrison et al, U.S.P. 1,828,464 10 dated October 20, 1931. Both of these patents show making of pulleys with a single v-groove, which can be used to contain and provide power to a v-belt. It is possible also to make pulleys having two v-shaped grooves by a metal spinning process, as shown in U. S. Patent 2,892,431 of Killian et al, dated 15 June 20, 1959. However, this involves more complicated machinery, and is also subject to difficulty because the formation of the v-grooves causes metal flow, leading to thinned portions of the pulley wall around the v-grooves which may lead to failure of the pulley in operation.
It has been proposed to form pulleys having more than two v-grooves by the use of metal dies, as has been disclosed in U.5.P. 3,368,376 of Previte, dated February 13, 1968. However, this process would require complicated dies with expanding ar-cuate segments. Another process, which involves the spinning of shallow grooves which are folded together into a sinuous shape and impressed with a v-grooved roller, has been proposed in U.S.P. 3,377,26~ of Sproul. This process also involves expanding die segments and complicated equipment~ and requires that very thin grooved metal be precisely folded together with-3Q out tearing. Insofar as Applicant is aware, neither the Previtenor the Sproul process has been used commercially.
The formation of v-grooves in the side of a pulley in any of the aforesaid processes can lead to thinning of the pulley wall, and therefore failure of the pulley. One reason for this is that a considerable amount of metal flow must necessarily occur in these processes, and it is difficult to guide this flow in such a way that all portions of the finished v-groove~
in the pulley are adequate thickness. ~ccordingly, it is necessary to start from a fairly heavv gauge meta:l, so that the final pulley will be of suf~icient strength to resist the tor-sional stresses which would tend to drive it out-of-round in operation.
The existiny spun pulleys have been usable with respect to single v-belts, which are belts having one flat side and one side shaped in an outwardly pointing vee configuration.
However, for many years, other belts, known as poly v-belts, have been used in a number of operations, such as for the powering of specialized machinery. These belts have one flat side and a plurality (usually six) of vee portions extending outwardly on the opposite side, in a saw-tooth pattern. The production of pulleys to engage such belts has been difficult, as the saw-tooth like configuration of a poly v-belt requires a number of sharply pointed vee configurations on the pulley, in relatively close proximity to one another. This uses up a great deal of metal. Accordingly, a relatively thick walled pulley can must be used if traditional metal spinning techniques, or a die stamping technique such as that of Previte, is to be employed. The resulting pulleys would be heavy and expensive to make, and have not found favour in automobile manufacture, where low cost and weight reduction are desirable ~or commer-cial acceptance. The lack of effective, low-cost, light-weight pulleys has prevented the widespread adoption of poly v-belts by the automobile industry, despite other inherent ad~anta~es which have been recognized for such belts.
In most spinning or die-stamping methods, the pulley blank is formed initially by drawing a flat piece of metal into a shape having a base and an upstanding cylindrical wall. This blank is commonly known as a "can". The pulley gxooves are rolled or die-stamped into the wall of the can. Accordingly, the initial flat piece of metal must be chosen to be of a sufficient thickness so that the can wall, after drawing, is of sufficient thickness to make ~-grooves of adequate strength for the intended application. However, the drawing process produces a wall which is either the same thickness as, or slightly thinner .
than, the base. Accordingly, in the known processes, the minimum thickness permissible for the starting piece oE metal is determined by the minimum thickness tolerable in the walls of the can. As the base is subjected to lesser stresses than the wall during formation of the pulley, it need not be as thick or strong as the wall. It 5 would therefore be advantageous in many cases, from a cost point of view, to provide a pulley can which has a strengthened wall.
Accordingly, it is the object of the present invention to provide a method for strengthening the approximately cylindrical wall portions of a pulley blank or "can" so that the wall portion 10 will be more robust than would otherwise be possible with the thick-ness of sheet metal used to form the pulley can. It is another ob-ject of the invention to prepare pulleys having at least four v-grooves in their sides, such v-grooves having relatively sharp bottoms to their vees. It is another object to form a generalized 15 method of thickening the sheet metal of vertical walls of a drawn can, so as to strengthen the vertical upstanding walls. It is an-other object to provide light-weight, strong pulleys for the purpose of powering poly v-belts in automobiles.
The invention provides a poly-v pulley formed from a 20 pulley can blank of sheet metal of a predetermined minimum permis-sible thickness comprising: a circular base of a wall thickness equal to said predetermined minimum permissible thickness, and an integral annular wall portion having a generally smooth cylindrical interior peripheral surface and an exterior peripheral surface 25 shaped to operatively engage a poly v-belt, said wall portion having a cross-sectional configuration defined by metal cold flow which is straight along its interior periphery and has a plurality of v grooves in its exterior periphery, the distance between the trough of each v groove and said straight interior periphery being suf-30 ficient to provide required strength but less than the predeterminedminimum thickness of said sheet metal can blank, the cross-sectional area of said wall portion being greater than the cross-sectional area of a section of said sheet metal can blank of said predeter-mined thickness having a length equal to the axial extent of said 35 wall portion whereby said pulley contains less metal and weighs less than a pulley with a similarly configured wall portion made from a can blank of the same metal having a thickness such that a . ~
length thexeof equal to the axlal extent of said wall portion has a cross-sectional area equal to or slightly greater than the cross-sectional area of said wall portion.
The invention also provides an improvement in a method of making a pulley from a pulley can blank o~ predetermined minimum per-5 missible thickness by forming a circular base from the pulley canblank with a thickness equal to the predetermined minimum thickness.
The improvement comprises forming integral with said base a thickened annular wall portion from said pulley can blank which has a thick~,s greater than said predetermined minimum thickness, said thickened 10 wall portion being formed by partially collapsing an annular section of the pulley can blank having an axial extent greater than the axial extent of said annular wall portion to an axial extent equal to that of said annular wall portion without materiall~ changing the thickness thereof but not completely such that interior surface 15 portions thereof are interengaged, and moving the partially collapsed section of the pulley can blank radially inwardly while restraining the same against axial expansion and radially inward movement beyond a predetermined radial position so that the interior peripheral surface area of said partially collapsed section is reduced without 20 portions thereof interengaging.
The roller as described above can be smoothly cylindrical and the predetermined distance can be greater than the thic]cness of the metal of the base, whereby a smooth-walled pulley with a robust wall thicker than the base and bounded by two flanges is obtained.
25 In another em~odiment, the~roller can have circumferential ridges whereby to impart a poly-v groove pattern on the face of the pulley between the flanges. In this case, the predetermined distance (between the part of the roller most closely approaching the backing block to the backing block) can be less than the thickness of the 3Q sheet metal of the pulley can, while still giving adequate strength.
In another embodiment, a smooth-walled pulley with a thickened wall is first formed, then this is contacted with a roller having circumferential ridges to give a poly-v grooved pulley.
The invention will be further described with respect to 35 the drawings in which:
Figure 1 represents a sheet of sheet metal which is u~ahle to form a pulley can.
Fiyure 2 is a cross-sectional view of one form of a pulley can formed ~rom the metal of Figure l.
Figures 2a and 2b show cross-sectional views of alternate forms of the base of the pulley can.
~igure 3 shows a cross-sectional view of the pulley can of Figure 2 mounted in a conventional metal spinning apparatus.
Figure 4a shows a partial cross-sectional view of the can of Figure 2 and Figure ~b shows a partial cross-sectional view of(the same can, illustrating a flange-forming step which can optionally be per~ormed prior to partial collapsing of the can.
Figure 5 shows a partial cross-sectional view of the can of Figure 2, showing one method of collapsing the can partlally.
Figures ~a and 6b show a partial cross-sectional view of the can of Figure 2, illustrating successive steps of an alter-native way of collapsing the can partially.
Figures7a and and 7b show successive steps in the forming of v-grooves in a partially collapsed can.
Figures 8a and 8b show successive steps is thickening the walls of a partially collapsed can without forming v-grooves.
Figure 9 shows the formation of v-grooves in a can after the step of Figure 8.
In its simplest form in manufacturing a pulley suitable for poly v-belt use on automo~iles, a pulley can is formed by deep drawing or spinning, in a conventional way, a sheet of flat metal. The particular sheet metal can be any of those con-ventionally used in spun pulley manufacture. The most common of these are sheet aluminum and hot rolle~, commercial quality, low carbon sheet steel. The sheet of sheet metal, such as shown in Figure l, has for example a thickness of O.OB0 inch. Thicker 3Q sheet metal can of course be used, and the upper limit to thick-ness depends upon the ultimàte use envisaged for the pulley to be made, and the pressures able to be exerted by the drawing and spinning equipment to be used. The use of thin sheet metal (io e., between 0.070 inch and 0.110 inch in thickness) is preferred as the particular advantayes of the present invention are much more pronounced when thin sheet metal is used, as then the in-vention provides pulleys from such thin sheet metal which have performance characteristics which could otherwise have only been obtained from pulleys made o~ a thicker grade of the particular sheet metal.
As stated above, a pulley blank (which is henceforth called a "can") is made according to conventional methods on a conven-tional deep drawing or rolling machine. Such a machine stamps a circular portion out of a sheet of sheet metal 1 (Figure 1) and draws it into a can having a base, and an upstanding cylindrical wall. The can may be of any desired dimension, depending upon the size of the equipment being used, and the size of the required final pulley. For example, for six inch pulleys (a size often used in automobiles) a circular piece nine inches in diameter is stamped out, and is drawn into a can with a ~.6 inch diameter base and a two inch high wall. A typical can is shown as 15 in Figure 2. The can of Figure 2 has a stepped base portion 10 and upstanding cylindrical wall 11. The base portion 10 is usually pierced in its center by a hole at 12 in conventional manner, to provide ~or registration on metal spinning equipment. Other holes may be pierced for registration purposes or for use as bolt holes when the pulley is completed. Additionally, the shape of the base 10 of the can need not be stepped as shown in Figure 2, but may instead be of flat or sloped configuration as shown in Figures 2a and 2b. Instead of a single hole, several holes may be pierced in the base in any desired pattern, as 2S shown at 13 in Figure 2b. If desired, the pulley blank may be f;tted with a hub formed of a separate piece of metal, as for example shown in United States Patent 2,696,74Q issued December 1, 1954.
According to the method of the invention, the can is placed in a conventional, general purpose, metal spinning machine.
Such machines are available commercially, and will not be illus-tra~ed here. As is usual, the machine is provided with chucks to hold a workpiece for rotation and with tool holders to move selected tools toward and away from the axis of rotation of the work-piece. The machine is also capable o~ compressin~ a work-piece along its axis of rotation.
Figure 3 shows a can of the form of ~igure 2 positioned in a metal spinning machine between bottom chuck 20, and top chuck 23. The axis of rotation of the can is shown by the line a~a through the chucks and the can. As is common in the pulley spinning art, the can is correctly oriented so that its axis of rotation is the centre axis of the cylindrical can wall. Such orientation can be achieved by means of a can holding groove 21 in the bottom chuck 20, and a central spindle 2~ extending from chuck 23 and engaging hole 12, or by any other known means.
If desired, cylindrical internal support block 60 may be secured to the chuck 20 for rotation therewith. The block 60 has an indentation 61, to house spindle 24 when chucks 23 and 20 are moved together a predetermined distance.
It is preferred, for reasons to be described later, that the inner side of groove 21 be sloped, rather than vertical, as indicated at 25 in Figure 3. Top chuck ~3 also has a sloping annular portion 26 facing the slope 25, also as shown in Figure 3.
If desired, a step of forming outer and inner flanges in the pulley wall can be carried out before thickening of the wall and forming the grooves in it. Such a step is not abso-lutely necessary, as flanges can conveniently be formed during the course of subsequent steps of pulley formation, as will be described. However, it is sometimes convenient to form the flanges first, as this may permit better control o~ the partial collapse of the pulley walll as described later.
The step of flange formation is shown in Figures 4a and 4b. Figures 4a shows a can positioned as shown in Figure 3, but with a roller 50 approaching it. The roller 50 is rotatable about an axis c-c parallel to a-a and is movable toward and away from axis a-a. The roller 50 has a generally cylindrical smooth outer ~ace 51, and two sloped portions 52 and 53 each adjacent to the cylindrical face 51 as shown in Figure 4a. A1-ternately, the $ace o~ the roller can be slightly concave if desired. As is knGwn in the art, such a roller can be mounted on springs, so that it can move axially up and down slightly in response to pressures on its periphery. In the example shown, the roller is unpowexed.
The chucks 20 and 23 are rotated simultaneously, at the same speed and in the same direction, carrying with them the can 15 and block 60. As this rotation is occurring, the roller 50 is moved into contact with the wall 11 o~ the can 15. Sim-ultaneously, chuck 23 is moved downwardly a predetermined dis-tance, so that, as the face 51 contacts the can wall 11 and con-tinues to move inwardly, the metal at the join between base 10 and wall 11 (shown at 16) is folded over by the pressure o~ the roller 51 bearing against the can. The sloping portion 52 of the roller helps fold over the metal at 16 smoothly, to form a flange. Similarly, the sloping portion 53 helps form a flange smoothly at the end 17 of the can wall which is most remote from the base. The roller 50 is moved inwardly toward the axis a-a a predetermined amount, having regard to the amount of downward movement of the chuck 23, so that the areas 16 and 17 of the wall 11 are folded into the position shown in Figure 4b, without undue stretching. Preferably (but not necessarily) the internal block 60 extends outwardly just sufficiently so that~s external face 62 provides a backing support for the wall 11, when the roller 50 is at the innermost limit of its travel towards the axis a-a. It is preferred, however, that the block 60 should be of such a height tha~ there is a gap, indicated as 63 between the base 10 an~ the block 60 after this operation, so that the chuck 23 can be moved in subsequent steps of the pulley forma-tion closer to the chuck 20, without the necessity of changing blocks 60. However, instead of leaving a space 63, it is also possible to dispense completely with the block ~0 during the step shown in Figures 4a and 4b~ or else, after completion of the step shown in Figures 4a and 4b, to remove the block 60 and replace it with a block having a smaller vertical height, before going on to further steps.
The steps shown in Figures 4a and 4b create two flanges, 18 and 19~ with a flat portion 117 between them. It will be noted that the flange 19 lies along the sloping portion 25 of the chuck 20 and is in fact formed between the sloping portion
MET~IOD OF PULLEY MANUFACTURE AND PRODUCT
This application relates to a method of thickening sheet metal in selected areas. In a more preferred embodiment, this application relates to a method of making pulleys from sheet metal.
The method of making pulleys from sheet metal has long been known. Such pulleys are often made by a metal spinning process, such as that shown in Wickwire et al, U.S.P. 2,685,856, dated August 10, 1954, or Harrison et al, U.S.P. 1,828,464 10 dated October 20, 1931. Both of these patents show making of pulleys with a single v-groove, which can be used to contain and provide power to a v-belt. It is possible also to make pulleys having two v-shaped grooves by a metal spinning process, as shown in U. S. Patent 2,892,431 of Killian et al, dated 15 June 20, 1959. However, this involves more complicated machinery, and is also subject to difficulty because the formation of the v-grooves causes metal flow, leading to thinned portions of the pulley wall around the v-grooves which may lead to failure of the pulley in operation.
It has been proposed to form pulleys having more than two v-grooves by the use of metal dies, as has been disclosed in U.5.P. 3,368,376 of Previte, dated February 13, 1968. However, this process would require complicated dies with expanding ar-cuate segments. Another process, which involves the spinning of shallow grooves which are folded together into a sinuous shape and impressed with a v-grooved roller, has been proposed in U.S.P. 3,377,26~ of Sproul. This process also involves expanding die segments and complicated equipment~ and requires that very thin grooved metal be precisely folded together with-3Q out tearing. Insofar as Applicant is aware, neither the Previtenor the Sproul process has been used commercially.
The formation of v-grooves in the side of a pulley in any of the aforesaid processes can lead to thinning of the pulley wall, and therefore failure of the pulley. One reason for this is that a considerable amount of metal flow must necessarily occur in these processes, and it is difficult to guide this flow in such a way that all portions of the finished v-groove~
in the pulley are adequate thickness. ~ccordingly, it is necessary to start from a fairly heavv gauge meta:l, so that the final pulley will be of suf~icient strength to resist the tor-sional stresses which would tend to drive it out-of-round in operation.
The existiny spun pulleys have been usable with respect to single v-belts, which are belts having one flat side and one side shaped in an outwardly pointing vee configuration.
However, for many years, other belts, known as poly v-belts, have been used in a number of operations, such as for the powering of specialized machinery. These belts have one flat side and a plurality (usually six) of vee portions extending outwardly on the opposite side, in a saw-tooth pattern. The production of pulleys to engage such belts has been difficult, as the saw-tooth like configuration of a poly v-belt requires a number of sharply pointed vee configurations on the pulley, in relatively close proximity to one another. This uses up a great deal of metal. Accordingly, a relatively thick walled pulley can must be used if traditional metal spinning techniques, or a die stamping technique such as that of Previte, is to be employed. The resulting pulleys would be heavy and expensive to make, and have not found favour in automobile manufacture, where low cost and weight reduction are desirable ~or commer-cial acceptance. The lack of effective, low-cost, light-weight pulleys has prevented the widespread adoption of poly v-belts by the automobile industry, despite other inherent ad~anta~es which have been recognized for such belts.
In most spinning or die-stamping methods, the pulley blank is formed initially by drawing a flat piece of metal into a shape having a base and an upstanding cylindrical wall. This blank is commonly known as a "can". The pulley gxooves are rolled or die-stamped into the wall of the can. Accordingly, the initial flat piece of metal must be chosen to be of a sufficient thickness so that the can wall, after drawing, is of sufficient thickness to make ~-grooves of adequate strength for the intended application. However, the drawing process produces a wall which is either the same thickness as, or slightly thinner .
than, the base. Accordingly, in the known processes, the minimum thickness permissible for the starting piece oE metal is determined by the minimum thickness tolerable in the walls of the can. As the base is subjected to lesser stresses than the wall during formation of the pulley, it need not be as thick or strong as the wall. It 5 would therefore be advantageous in many cases, from a cost point of view, to provide a pulley can which has a strengthened wall.
Accordingly, it is the object of the present invention to provide a method for strengthening the approximately cylindrical wall portions of a pulley blank or "can" so that the wall portion 10 will be more robust than would otherwise be possible with the thick-ness of sheet metal used to form the pulley can. It is another ob-ject of the invention to prepare pulleys having at least four v-grooves in their sides, such v-grooves having relatively sharp bottoms to their vees. It is another object to form a generalized 15 method of thickening the sheet metal of vertical walls of a drawn can, so as to strengthen the vertical upstanding walls. It is an-other object to provide light-weight, strong pulleys for the purpose of powering poly v-belts in automobiles.
The invention provides a poly-v pulley formed from a 20 pulley can blank of sheet metal of a predetermined minimum permis-sible thickness comprising: a circular base of a wall thickness equal to said predetermined minimum permissible thickness, and an integral annular wall portion having a generally smooth cylindrical interior peripheral surface and an exterior peripheral surface 25 shaped to operatively engage a poly v-belt, said wall portion having a cross-sectional configuration defined by metal cold flow which is straight along its interior periphery and has a plurality of v grooves in its exterior periphery, the distance between the trough of each v groove and said straight interior periphery being suf-30 ficient to provide required strength but less than the predeterminedminimum thickness of said sheet metal can blank, the cross-sectional area of said wall portion being greater than the cross-sectional area of a section of said sheet metal can blank of said predeter-mined thickness having a length equal to the axial extent of said 35 wall portion whereby said pulley contains less metal and weighs less than a pulley with a similarly configured wall portion made from a can blank of the same metal having a thickness such that a . ~
length thexeof equal to the axlal extent of said wall portion has a cross-sectional area equal to or slightly greater than the cross-sectional area of said wall portion.
The invention also provides an improvement in a method of making a pulley from a pulley can blank o~ predetermined minimum per-5 missible thickness by forming a circular base from the pulley canblank with a thickness equal to the predetermined minimum thickness.
The improvement comprises forming integral with said base a thickened annular wall portion from said pulley can blank which has a thick~,s greater than said predetermined minimum thickness, said thickened 10 wall portion being formed by partially collapsing an annular section of the pulley can blank having an axial extent greater than the axial extent of said annular wall portion to an axial extent equal to that of said annular wall portion without materiall~ changing the thickness thereof but not completely such that interior surface 15 portions thereof are interengaged, and moving the partially collapsed section of the pulley can blank radially inwardly while restraining the same against axial expansion and radially inward movement beyond a predetermined radial position so that the interior peripheral surface area of said partially collapsed section is reduced without 20 portions thereof interengaging.
The roller as described above can be smoothly cylindrical and the predetermined distance can be greater than the thic]cness of the metal of the base, whereby a smooth-walled pulley with a robust wall thicker than the base and bounded by two flanges is obtained.
25 In another em~odiment, the~roller can have circumferential ridges whereby to impart a poly-v groove pattern on the face of the pulley between the flanges. In this case, the predetermined distance (between the part of the roller most closely approaching the backing block to the backing block) can be less than the thickness of the 3Q sheet metal of the pulley can, while still giving adequate strength.
In another embodiment, a smooth-walled pulley with a thickened wall is first formed, then this is contacted with a roller having circumferential ridges to give a poly-v grooved pulley.
The invention will be further described with respect to 35 the drawings in which:
Figure 1 represents a sheet of sheet metal which is u~ahle to form a pulley can.
Fiyure 2 is a cross-sectional view of one form of a pulley can formed ~rom the metal of Figure l.
Figures 2a and 2b show cross-sectional views of alternate forms of the base of the pulley can.
~igure 3 shows a cross-sectional view of the pulley can of Figure 2 mounted in a conventional metal spinning apparatus.
Figure 4a shows a partial cross-sectional view of the can of Figure 2 and Figure ~b shows a partial cross-sectional view of(the same can, illustrating a flange-forming step which can optionally be per~ormed prior to partial collapsing of the can.
Figure 5 shows a partial cross-sectional view of the can of Figure 2, showing one method of collapsing the can partlally.
Figures ~a and 6b show a partial cross-sectional view of the can of Figure 2, illustrating successive steps of an alter-native way of collapsing the can partially.
Figures7a and and 7b show successive steps in the forming of v-grooves in a partially collapsed can.
Figures 8a and 8b show successive steps is thickening the walls of a partially collapsed can without forming v-grooves.
Figure 9 shows the formation of v-grooves in a can after the step of Figure 8.
In its simplest form in manufacturing a pulley suitable for poly v-belt use on automo~iles, a pulley can is formed by deep drawing or spinning, in a conventional way, a sheet of flat metal. The particular sheet metal can be any of those con-ventionally used in spun pulley manufacture. The most common of these are sheet aluminum and hot rolle~, commercial quality, low carbon sheet steel. The sheet of sheet metal, such as shown in Figure l, has for example a thickness of O.OB0 inch. Thicker 3Q sheet metal can of course be used, and the upper limit to thick-ness depends upon the ultimàte use envisaged for the pulley to be made, and the pressures able to be exerted by the drawing and spinning equipment to be used. The use of thin sheet metal (io e., between 0.070 inch and 0.110 inch in thickness) is preferred as the particular advantayes of the present invention are much more pronounced when thin sheet metal is used, as then the in-vention provides pulleys from such thin sheet metal which have performance characteristics which could otherwise have only been obtained from pulleys made o~ a thicker grade of the particular sheet metal.
As stated above, a pulley blank (which is henceforth called a "can") is made according to conventional methods on a conven-tional deep drawing or rolling machine. Such a machine stamps a circular portion out of a sheet of sheet metal 1 (Figure 1) and draws it into a can having a base, and an upstanding cylindrical wall. The can may be of any desired dimension, depending upon the size of the equipment being used, and the size of the required final pulley. For example, for six inch pulleys (a size often used in automobiles) a circular piece nine inches in diameter is stamped out, and is drawn into a can with a ~.6 inch diameter base and a two inch high wall. A typical can is shown as 15 in Figure 2. The can of Figure 2 has a stepped base portion 10 and upstanding cylindrical wall 11. The base portion 10 is usually pierced in its center by a hole at 12 in conventional manner, to provide ~or registration on metal spinning equipment. Other holes may be pierced for registration purposes or for use as bolt holes when the pulley is completed. Additionally, the shape of the base 10 of the can need not be stepped as shown in Figure 2, but may instead be of flat or sloped configuration as shown in Figures 2a and 2b. Instead of a single hole, several holes may be pierced in the base in any desired pattern, as 2S shown at 13 in Figure 2b. If desired, the pulley blank may be f;tted with a hub formed of a separate piece of metal, as for example shown in United States Patent 2,696,74Q issued December 1, 1954.
According to the method of the invention, the can is placed in a conventional, general purpose, metal spinning machine.
Such machines are available commercially, and will not be illus-tra~ed here. As is usual, the machine is provided with chucks to hold a workpiece for rotation and with tool holders to move selected tools toward and away from the axis of rotation of the work-piece. The machine is also capable o~ compressin~ a work-piece along its axis of rotation.
Figure 3 shows a can of the form of ~igure 2 positioned in a metal spinning machine between bottom chuck 20, and top chuck 23. The axis of rotation of the can is shown by the line a~a through the chucks and the can. As is common in the pulley spinning art, the can is correctly oriented so that its axis of rotation is the centre axis of the cylindrical can wall. Such orientation can be achieved by means of a can holding groove 21 in the bottom chuck 20, and a central spindle 2~ extending from chuck 23 and engaging hole 12, or by any other known means.
If desired, cylindrical internal support block 60 may be secured to the chuck 20 for rotation therewith. The block 60 has an indentation 61, to house spindle 24 when chucks 23 and 20 are moved together a predetermined distance.
It is preferred, for reasons to be described later, that the inner side of groove 21 be sloped, rather than vertical, as indicated at 25 in Figure 3. Top chuck ~3 also has a sloping annular portion 26 facing the slope 25, also as shown in Figure 3.
If desired, a step of forming outer and inner flanges in the pulley wall can be carried out before thickening of the wall and forming the grooves in it. Such a step is not abso-lutely necessary, as flanges can conveniently be formed during the course of subsequent steps of pulley formation, as will be described. However, it is sometimes convenient to form the flanges first, as this may permit better control o~ the partial collapse of the pulley walll as described later.
The step of flange formation is shown in Figures 4a and 4b. Figures 4a shows a can positioned as shown in Figure 3, but with a roller 50 approaching it. The roller 50 is rotatable about an axis c-c parallel to a-a and is movable toward and away from axis a-a. The roller 50 has a generally cylindrical smooth outer ~ace 51, and two sloped portions 52 and 53 each adjacent to the cylindrical face 51 as shown in Figure 4a. A1-ternately, the $ace o~ the roller can be slightly concave if desired. As is knGwn in the art, such a roller can be mounted on springs, so that it can move axially up and down slightly in response to pressures on its periphery. In the example shown, the roller is unpowexed.
The chucks 20 and 23 are rotated simultaneously, at the same speed and in the same direction, carrying with them the can 15 and block 60. As this rotation is occurring, the roller 50 is moved into contact with the wall 11 o~ the can 15. Sim-ultaneously, chuck 23 is moved downwardly a predetermined dis-tance, so that, as the face 51 contacts the can wall 11 and con-tinues to move inwardly, the metal at the join between base 10 and wall 11 (shown at 16) is folded over by the pressure o~ the roller 51 bearing against the can. The sloping portion 52 of the roller helps fold over the metal at 16 smoothly, to form a flange. Similarly, the sloping portion 53 helps form a flange smoothly at the end 17 of the can wall which is most remote from the base. The roller 50 is moved inwardly toward the axis a-a a predetermined amount, having regard to the amount of downward movement of the chuck 23, so that the areas 16 and 17 of the wall 11 are folded into the position shown in Figure 4b, without undue stretching. Preferably (but not necessarily) the internal block 60 extends outwardly just sufficiently so that~s external face 62 provides a backing support for the wall 11, when the roller 50 is at the innermost limit of its travel towards the axis a-a. It is preferred, however, that the block 60 should be of such a height tha~ there is a gap, indicated as 63 between the base 10 an~ the block 60 after this operation, so that the chuck 23 can be moved in subsequent steps of the pulley forma-tion closer to the chuck 20, without the necessity of changing blocks 60. However, instead of leaving a space 63, it is also possible to dispense completely with the block ~0 during the step shown in Figures 4a and 4b~ or else, after completion of the step shown in Figures 4a and 4b, to remove the block 60 and replace it with a block having a smaller vertical height, before going on to further steps.
The steps shown in Figures 4a and 4b create two flanges, 18 and 19~ with a flat portion 117 between them. It will be noted that the flange 19 lies along the sloping portion 25 of the chuck 20 and is in fact formed between the sloping portion
2~
g 53 of the roller 50 and the sloping portiorl 25 of the chuck 20.
The slope of portion 25 should be pre-chosen so that it wil]
provide a smooth back to assist in formation of flange 19.
As stated above, the step shown in Figures 4a and 4b is optional. It has the effect of accurately sizing two flanges 18 and 19, which flanges are found to be useful in pulleys for poly v-belts, as they help to retain the poly v-belt in position when the pulley is ultimately formed. In the subsequent description, it will be assumed that the step of flange formation as shown in Figures 4a and 4b has not been carried out, but it will be under-stood by one skilled in the art that the steps to be described can be carried out with a pulley blank having flanges 18 and 19 as obtained from the carrying out of the steps shown in Figures 4a and 4b.
If the step of Figures 4a and 4b is not carried out, the first step to be performed on a pulley can in the process accor-ding to the invention is the partial collapsing of the wall 11 of the pulley can 15. Such partial collapsing can be carried out in several ways. One way (which is not preferred) is by a step of bulging the can as shown in U. S. Patent 2,929,345 of Zatyko, dated March 22, 1960. This step is not preferred as it requires special equîpment, which must be specially mounted on the spinning machine for the purpose of the step, and subsequently removed so that other steps can be carried out. An alternative, and also not preferred manner, is simply to apply axial pressure to the chuck 23, causing the wall 11 to buckle, as shown at 112 in Figure 5. The buckling occurs in an irregular manner. The block 60 need not be present during the operation of partial collapse of the wall 11 to the approximate shape shown at 112, but i~ can be present if desired. As will be obvious to one skilled in the art, the irregular buckling could also be carried out after flanges 18 and 19 have been formed by the method shown in Figures 4a and 4b.
An alternative~ and preferred manner of partially collap-sing the wall 11 is shown in Fi~ures 6a and 6b. Fi~ures 6a and 6b show a pair of rollers 31 and 32, which rotate about an axis ., ~2~2~
b-b. These rollers are separated fron~ one another by a compres-sion spring 33. Each of the rollers has a face with a sloping portion 3~, a blunt extension 35, and a curved portion 36, which is located nearest the other roller. The two rollers are sepa rated by the spring 33 a distance such that the projections 35 will engage wall 11, when the rollers 32 and 33 are moved to-gether toward the wall, at fairly widely spaced points on wall 11 . .
In the partial collapse of the can wall according to the method of Figures 6a and 6b, the chucks 20 and 23 are powered to rotate the can 11, and the rollers 31 and 32 are moved into ~on-tact with the can 11. As the rollers contact the can 11, they will o~ course begin rotating as well~ as the rotation of the can 11 will cause them to rotate. The projections 35 will of course be the first portions of rollers 31 and 32 to contact ~he can wall 11 As soon as the portions 35 have contacted the wall, the chuck 23 is moved toward the chuck 20, at the same time as the rollers 32 and 31 are moved together toward the axis a-a.
This will cause the can wall 11 to buckle, and, at the same time, the buckli~g will be controlled somewhat by the fact that the projections 35 will tend to stay in contact with the same portion of the can wall that they originally contacted, with the spring 33 compressing as the chuck 23 moves toward the chuck 20. This will cause the can walI to lie along the contour of the curved roller face 36, as shown in Figure 6b. The amount by which the rollers 31 and 32 should aporoach the axis a-a, and the design of the contours 36 and the amount of movement of the chuck 23 will be obvious to a man skilled in the art. It is generally preferred to have the rollers 31 and 32 end up in face-to-face contact with one another, so that no point or burr on the metal is formed ~y a gap between the two faces 36, such as indicated at 37. However, if a burr or point is formed~ this is not de-trimental, as it will be removed during the later processing steps. After the rollers 31 adn 32 are withdrawn further con-trolled collapse can be carried out by moving the chucks 20 and23 closer to one another by a desired amount.
~;2Z~ 9 The form oE partially collapsed wall formed by the method of Figures 6a and 6b is shown in Figure 6b at 113. It will be noted that the shape of the collapsed wall is somewhat more regular than is formed by the method of Figure 5. Hereinafter, further steps of the invention will be described with respect to a wall of form 112, but it is understood that this disclosure applies equally to a wall of form 113.
No matter which method is used to collapse the wall, it is preferred that the wall 11 be collapsed so that its final height (hl) (see Figure 5) is from ! 25~ to 75% of its original height h ~see Figure 2). If a flange has been formed by the step of Figure 4 prior to the collapse, the "collapsed" height hl includes the height of the flanges 18 and 19. Conveniently, the height of block 60 is such that, after collapse has occurred by the desired amount, the block is in contact with the base 10 of the can, as shown in Figures 5 and 7a.
Once the wall has been collapsed into the shape 112 or 113, the operator can, according to the invention, either perform on it the steps of Figures 7a and 7b to obtain a final pulley suit-able for use with a poly-v-groove belt, or else the steps of Figures 8a and 8b to obtain a pulley having a thickened upright wall and which is suitable for use with a flat belt. If the steps of Figures 8a and 8b are carried out, a subsequent stap can (if desired) be carried out as is shown in Figure 9, to con-vert the pulley thus formed into one suitable for use with a polyv-belt.
Referring now to Figures 7a and 7b, one method of forming a pulley suitable for use with a poly v-belt from a collapsed can having the configuration 112 or 113, will now be described.
3Q Figure 7a shows a roller 40, which rotates about an axis d-d, parallel to the axis a-a. The face of roller 40 is provided with a number of sharp projections 41, spaced from one another by v-shaped indentations 42. The number and shape of projections 41 is the same as the number and shape of projections on the poly v~belt with which the pulley to be made is intended to be used.
In the example shown in Figure 7a, there are six projections 41 separated by five indentations 42, in the same configuration as ~2~
is used in a common type of v-belt. The top of the roller 40 has a sloped transition surface 43 between its face and its top.
Similarly, there is a sloped transition surface 44 between the face and the bottom of the rol]er.
The chucks 20 and 23 are set into motion simultaneously and in the same direction, causing the partially collapsed can to rotate. The axis d-d is then moved toward the axis a-a.
When the face of the roller 40 comes ir. contact with the can, the roller also begins to rotate. The surface 43, as it engages the can, squeezes a portion 114 of the metal of the can wall against the sloped surface 26 of upper chuck 23, forming a ~lange. Similarly, the sloped surface 44 squeezes a portion 115 of metal against the sloped surface 25 of bottom chuck 20, for-ming a bottom flange. These two flanges are identical with the flanges formed at 18 and 19 in the step described with respect to Figure 4. If the step of Figure 4 has been carried out, and the flanges are already formed, the slo~ed portions 43 and 44 merely nest against the pre-existing flanges, and do little if any deformation of metal.
The sharp projections 42 cut into the metal of the can wall 112, and deform it. If the can wall were not partially collapsed, i.e., if it were in the same state as is shown in Figure 2 at 11, the sharp projections would cut deeply into the thin sheet metal of the wall. If the sheet metal were relatively thin, i.e., ~elow about .110 inch, and the depth of the indentations 42 from tha projections 41 was approximately .125 inch, insufficient metal would flow into the indentations 42 to fill such indenta-tions before the sharp projections 41 cut entirely through the metal of wall 11, or else approached so nearly as to cutting through the wall as to render the wall 11 extremely weak. How-ever, according to the method of the invention, the collapsed portion 112 of the wall provides more metal than a straight cylindrical wall would do. This gives sufficient metal, even when sheet metal of initial thickness of 0.080 inch is used, to fill completely Q.125 inch indentations at 42 t while still re-taining a strong wall.
, , ~2~
The roller 4Q is moved towards axis a-a until the indenta-tions 42 have all been filled wi~h metal. The final form of the can wall is shown in ~igure 7b. It will be not~d that there is an appreciable thickness of metal indicated by the distance y between the points 41 and the inside 116 of the can wall which now rests firmly against the exterior wall Ç2 of the backing block 60. The indentations 42 are fully filled with metal of the wall, as shown by the dimension x. Generally speaking, where the height hl is rom .25 to .75 of the height h , a thickness of wall plus projections (dimensions y`plus x in Figure 7b) of from about 1.5 to 2.5 of the thickness of the original sheet metal can be obtained for sheet metals in the thickness range of about .Q7~ inch to 0~130 inch The relative size of dimensions y and x will of course depend on the size, shape and number of projectIons 42, and upon how close to the wall 62 and the roller ~0 is allowed ~o approach. In order to obtain a strong pulley for use in an automobile, the roller 40 is allowed to ap~roach the wall 62 only closely enough so that the minimum wall thick-ness 7 will be 0.040 inch. A smaller minimum thickness would of course be permissible if the pulley were designed for uses requiring less strength.
During the operation of Figure 7~ the backing block 60 is extremely important, as its walls 62 assists in distributing the metal o~ can wall 112 so that it fills all of the indentations 42.
After the roller 40 has come to the position of Figure 7b, it is removed, and the pulley can, which has now been fully for-med into a pulley suitable for use with a poly v-belt, is re-moved. It will be noted that the pulley thus formed has two flanges, 18 and 19, which give it considerable dimensional sta-bility, and has a series o~ grooves (the mirror image of pro-jections 41 and indentations 42 of the roller) for use with a poly v-belt.
An alternative arrangement, for use in making a pulley with a flat face! is shown in Figures 8a and 8b. Turning first to Figure 8a, a roller 70, rotating around an axis e-e which is parallel to axis a-a is shown.This roller has a flat face 71 -` ~a2~ 9 .
and two sloped portions 72 and 73. Portion 72 joins the flat face 71 to the top of the roller, whereas portion 73 joins the flat face to the bottom of the roller. The width of the face 71 is just slightly smaller than the width of the face 62 of backing block 60, and the slope o~ the sloped surfaces 72 and 73 are chosen having regard to the slopes of surface 26 and 25 with which they will co-act to form flanges.
The chucks 20 and 23 are caused to rotate simultaneously and in the same direction, carrying the can 20 with them. The axis e-e of the roller 70 is caused to move toward the axis a-a, with the roller oriented opposite the can as shown in Figure 8a.
The flat face 71 contacts the collapsed portion 112 of the can wall, pushing it against wali 62 of backing block 60. Simul-taneously, sloped surface 72 of roller 70 squeezes a ~ortion of the metal of the can wall against surface 26 of chuck 23, to form a flange, and surface 73 squeezes a portion of the metal of the can wall against sloped surface 25, also forming a flange.
Because of the bulged or partially collapsed surface of the wall of the canj there is more metal than would be needed merely to make a flat wall of the same thickness as the metal of the base.
Thus, when the roller 70 approaches the wall 62, a thick, smooth wall of metal 111 is formed, having smooth surfaces against faces 71 and 62. The advance o~ the roller 70 is stopped at a pre-determined place having regard to the amount of collapse which has been carried out in forming the buckled or collapsing wall 112, such that the newly formed wall 111 will be of a de-sired thickness. Generally, the thickness obtained will be somewhat in excess of the sheet ~etal forming the base 10 (ex-cluding any strengthening members or hubs) such as about from 3Q 1 1/4 to 2 times (preferably 1 1/3 to 1 1/2 times~ the thickness o~ the base 10. Obviously, if the roller 70 were advanced closer to the axis a-a, excess metal could squeeze out around the edges of the roller, leading to a thinner wall 111, but this would not be desirable, and does not form part o~ this invention. Having regard to the teachings herein a person skilled in the art can easily determine the amount of collapse required to give a suitable thickness 111, as h~ mav requireO
~Z~2~3~
If the flanges 18 and 19 have been preformed, as shown in Figures 4a and 4b, then the faces 72 and 73 will not in them-selves form flanges, but will merely mate smoothly against the pre-existing flanges 18 and 19, preventing metal from escaping from the area between face 62 and face 71, where the new, thicker wall 111 is being fcrmed.
After the condition shown in Figure 8b has been reached, the roller 70 is withdrawn, and the pulley can is removed from the chucks 20 and 23. A pulley can having a smooth, robust wall 111 has been formed, which is suitable as a pulley for a flat belt. The pulley also has flanges 18 and 19, which serve to retain the belt in place.
It will be noted that the steps of Figures 7 and $ each result intrinsically in a pulley having flanges 18 and 19.
Generally, it is preferred to retain these flanges, and one of the advantages of the invention is that the flange reduces the possibility o slippage of v-belts from pulleys formed according to the invention. However, it is possible, if desired, to remove the flanges 18 and 19 by means of a roller which nips off the flanges (as is known in the spun pulley art for removing un-wanted flanges or burrs) or by other conventional methods.
Therefore, although the flanges form a very desirable part of the invention, it is understood that unflanged pulleys also can be made by a process according to the invention.
If desired, instead of removing the pulley as formed with wall 111 from the chucks 20 and 23, the pulley can instead be subjected to the application of roller 40, as shown in Fig. 9, ~ollowing the steps shown in Figures 8a and ~b. The roller 40 approaches in a manner similar to that described with respect to Figures 7a and 7b, but, on this occasion, it engages flat, thick wall 111, rather than the bu-kled wall 112. However, the result obtained is the same as was obtained by the steps described in Figures 7a and 7b, as can be seen by comparing Figure 9 to Figure 7b.
In the foregoing disclosure, the contacting of the various rollers with the surface of the can wall has been accomplished by rotating the two chucks 20 and 23 at the same speed and in ~222~3~39 the same direction, entraining the can 15 along with them. The roller or rollers which then contact the surface of the can wall (such as, for example roller 40 or roller 70) axe freely rota-table, but are not powered. When they contact the can wall, they are caused to rotate by their contact with the rotating ca.n, at the same speed as the rotating can. It is of course within the scope of the invention to have the chucks 20 and 23 freely rotatable, and instead to power the roller which approa-ches the can wall. Alternately (although this is not preferred) both the roller and the chucks 20 and 23 could be powered so that both the can and the rolle~ are caused to rotate. The directions of rotation should preferably be such that, at the point of con-tact of the roller and the can, the two are moving in the same direction. However, they need not be moving at exactly the same speed, and, under`some circumstances, it is even possible to obtain good results with the can and the roller moving in dif-ferent directions, although this is not preferred.
Certain examples of the making of pulleys according to the disclosure given herein will no~ be given.
EXAMPLE I
: A can of the form shown in Figure 2 is dra~n by conventional means from sheet steel of thickness of 0.080 inches to have a width of 6.6 inches and a height h of 2.0 inches. The can is collapsed according to the step shown in Figure 5 to a height hl of 1.0 inch. The method steps with respect to Figure 7a and 7b are then performed on the can using a rollér 40 having six grooves spaced 0.140 inches from one another and having a depth of indentation 42 of 0.140 inches. The roller 40 is moved ~oward axis a-a ~ntil the distance between wall 62 and the projections 3Q 42 is 0.050 inches. When the roller 40 is removed and the can is removed from the chucks, it is found to be a well formed grooved pulley havi.ng two flanges (18 and 19 in the drawings) of approximately 6.6 inches in diameter and a central v-belt receiving portion having an average diameter of 6.0 inches and having six grooves corresponding to projections 41. ~ach of these grooves is 0.140 inches in depth, and the total depth of metal measured from the bottom of a vee to the inside of the . ,i ~L~2~
can (the distance y in Figure 7b) is 0.050 inches. The variation of depth between the six v-grooves is insi.gnificant, being less than .002 inches. The dimensions are substantiall~ constant around the diameter of a pulley.
EXA~PLE II
A sheet of sheet steel 0.080 inches in thickness is pre-formed into a can of the same shape as that described in Example I. The can is collapsed according to the step shown in Figure 5 to a height h1 of 1.0 inch. The steps illustrated in Figures 8a and 8b are carried out on the can. The roller 70 is allowed to approach the wall 60 such that the distance between face 71 and face 62 is 0.120 inches. When the roller 70 is withdrawn, and the can is removed from the chucks 20 and 22, it is found to have a v-belt receiving portion 6.0 inches in diameter and two flanges approximately 6.6 inches in diameter at each side of the v-belt receiving portion, The thickness of the wall of the v-belt re-ceiving portion is 0.120 inches, and the pulley is smoothly cy-lindrical in its v-belt receiving portion.
EXAMPLE III
_ _ . .
A pulley formed according to the teachings of Example II
is treated by a subsequent step as illustrated in Figure 9 and the associated disclosure. The roller 4~ is permitted to ap proach so that the projections 42 are a distance of 0.050 inches f`rom the face 62. When the roller is withdrawn and the can is removed from the chucks 20-and 23, a poly v-belt which is indis-tinguishable from the pulley formed in Example I is formed.
Each of the pulleys formed in Exampl~ I~ II and III is found to be highly resistant to being forced out of round, and is judged to be suitable for automotive and indeed heavy truck applications.
It is understood that the invention is not limited to the exact roller structure shown, nor to the exact pulley shapes illustrated, because the particular shapes of the rollers can be var;ed to provide other structural embodiments without de-parting from the scope of the present invention.
Having now described the features of the invention, andthe construction and operation of the preferred embodiments of - 18 ~
the novel method and th~ products provided by them, the inventor wishes it unde.rstood that the protection clai.med is not limited to the exact embodiments shown, but includes such modifications thereof as will be obvious to persons skilled in the art, and that the protection claimed is therefore limited only as set out in the appended claims.
g 53 of the roller 50 and the sloping portiorl 25 of the chuck 20.
The slope of portion 25 should be pre-chosen so that it wil]
provide a smooth back to assist in formation of flange 19.
As stated above, the step shown in Figures 4a and 4b is optional. It has the effect of accurately sizing two flanges 18 and 19, which flanges are found to be useful in pulleys for poly v-belts, as they help to retain the poly v-belt in position when the pulley is ultimately formed. In the subsequent description, it will be assumed that the step of flange formation as shown in Figures 4a and 4b has not been carried out, but it will be under-stood by one skilled in the art that the steps to be described can be carried out with a pulley blank having flanges 18 and 19 as obtained from the carrying out of the steps shown in Figures 4a and 4b.
If the step of Figures 4a and 4b is not carried out, the first step to be performed on a pulley can in the process accor-ding to the invention is the partial collapsing of the wall 11 of the pulley can 15. Such partial collapsing can be carried out in several ways. One way (which is not preferred) is by a step of bulging the can as shown in U. S. Patent 2,929,345 of Zatyko, dated March 22, 1960. This step is not preferred as it requires special equîpment, which must be specially mounted on the spinning machine for the purpose of the step, and subsequently removed so that other steps can be carried out. An alternative, and also not preferred manner, is simply to apply axial pressure to the chuck 23, causing the wall 11 to buckle, as shown at 112 in Figure 5. The buckling occurs in an irregular manner. The block 60 need not be present during the operation of partial collapse of the wall 11 to the approximate shape shown at 112, but i~ can be present if desired. As will be obvious to one skilled in the art, the irregular buckling could also be carried out after flanges 18 and 19 have been formed by the method shown in Figures 4a and 4b.
An alternative~ and preferred manner of partially collap-sing the wall 11 is shown in Fi~ures 6a and 6b. Fi~ures 6a and 6b show a pair of rollers 31 and 32, which rotate about an axis ., ~2~2~
b-b. These rollers are separated fron~ one another by a compres-sion spring 33. Each of the rollers has a face with a sloping portion 3~, a blunt extension 35, and a curved portion 36, which is located nearest the other roller. The two rollers are sepa rated by the spring 33 a distance such that the projections 35 will engage wall 11, when the rollers 32 and 33 are moved to-gether toward the wall, at fairly widely spaced points on wall 11 . .
In the partial collapse of the can wall according to the method of Figures 6a and 6b, the chucks 20 and 23 are powered to rotate the can 11, and the rollers 31 and 32 are moved into ~on-tact with the can 11. As the rollers contact the can 11, they will o~ course begin rotating as well~ as the rotation of the can 11 will cause them to rotate. The projections 35 will of course be the first portions of rollers 31 and 32 to contact ~he can wall 11 As soon as the portions 35 have contacted the wall, the chuck 23 is moved toward the chuck 20, at the same time as the rollers 32 and 31 are moved together toward the axis a-a.
This will cause the can wall 11 to buckle, and, at the same time, the buckli~g will be controlled somewhat by the fact that the projections 35 will tend to stay in contact with the same portion of the can wall that they originally contacted, with the spring 33 compressing as the chuck 23 moves toward the chuck 20. This will cause the can walI to lie along the contour of the curved roller face 36, as shown in Figure 6b. The amount by which the rollers 31 and 32 should aporoach the axis a-a, and the design of the contours 36 and the amount of movement of the chuck 23 will be obvious to a man skilled in the art. It is generally preferred to have the rollers 31 and 32 end up in face-to-face contact with one another, so that no point or burr on the metal is formed ~y a gap between the two faces 36, such as indicated at 37. However, if a burr or point is formed~ this is not de-trimental, as it will be removed during the later processing steps. After the rollers 31 adn 32 are withdrawn further con-trolled collapse can be carried out by moving the chucks 20 and23 closer to one another by a desired amount.
~;2Z~ 9 The form oE partially collapsed wall formed by the method of Figures 6a and 6b is shown in Figure 6b at 113. It will be noted that the shape of the collapsed wall is somewhat more regular than is formed by the method of Figure 5. Hereinafter, further steps of the invention will be described with respect to a wall of form 112, but it is understood that this disclosure applies equally to a wall of form 113.
No matter which method is used to collapse the wall, it is preferred that the wall 11 be collapsed so that its final height (hl) (see Figure 5) is from ! 25~ to 75% of its original height h ~see Figure 2). If a flange has been formed by the step of Figure 4 prior to the collapse, the "collapsed" height hl includes the height of the flanges 18 and 19. Conveniently, the height of block 60 is such that, after collapse has occurred by the desired amount, the block is in contact with the base 10 of the can, as shown in Figures 5 and 7a.
Once the wall has been collapsed into the shape 112 or 113, the operator can, according to the invention, either perform on it the steps of Figures 7a and 7b to obtain a final pulley suit-able for use with a poly-v-groove belt, or else the steps of Figures 8a and 8b to obtain a pulley having a thickened upright wall and which is suitable for use with a flat belt. If the steps of Figures 8a and 8b are carried out, a subsequent stap can (if desired) be carried out as is shown in Figure 9, to con-vert the pulley thus formed into one suitable for use with a polyv-belt.
Referring now to Figures 7a and 7b, one method of forming a pulley suitable for use with a poly v-belt from a collapsed can having the configuration 112 or 113, will now be described.
3Q Figure 7a shows a roller 40, which rotates about an axis d-d, parallel to the axis a-a. The face of roller 40 is provided with a number of sharp projections 41, spaced from one another by v-shaped indentations 42. The number and shape of projections 41 is the same as the number and shape of projections on the poly v~belt with which the pulley to be made is intended to be used.
In the example shown in Figure 7a, there are six projections 41 separated by five indentations 42, in the same configuration as ~2~
is used in a common type of v-belt. The top of the roller 40 has a sloped transition surface 43 between its face and its top.
Similarly, there is a sloped transition surface 44 between the face and the bottom of the rol]er.
The chucks 20 and 23 are set into motion simultaneously and in the same direction, causing the partially collapsed can to rotate. The axis d-d is then moved toward the axis a-a.
When the face of the roller 40 comes ir. contact with the can, the roller also begins to rotate. The surface 43, as it engages the can, squeezes a portion 114 of the metal of the can wall against the sloped surface 26 of upper chuck 23, forming a ~lange. Similarly, the sloped surface 44 squeezes a portion 115 of metal against the sloped surface 25 of bottom chuck 20, for-ming a bottom flange. These two flanges are identical with the flanges formed at 18 and 19 in the step described with respect to Figure 4. If the step of Figure 4 has been carried out, and the flanges are already formed, the slo~ed portions 43 and 44 merely nest against the pre-existing flanges, and do little if any deformation of metal.
The sharp projections 42 cut into the metal of the can wall 112, and deform it. If the can wall were not partially collapsed, i.e., if it were in the same state as is shown in Figure 2 at 11, the sharp projections would cut deeply into the thin sheet metal of the wall. If the sheet metal were relatively thin, i.e., ~elow about .110 inch, and the depth of the indentations 42 from tha projections 41 was approximately .125 inch, insufficient metal would flow into the indentations 42 to fill such indenta-tions before the sharp projections 41 cut entirely through the metal of wall 11, or else approached so nearly as to cutting through the wall as to render the wall 11 extremely weak. How-ever, according to the method of the invention, the collapsed portion 112 of the wall provides more metal than a straight cylindrical wall would do. This gives sufficient metal, even when sheet metal of initial thickness of 0.080 inch is used, to fill completely Q.125 inch indentations at 42 t while still re-taining a strong wall.
, , ~2~
The roller 4Q is moved towards axis a-a until the indenta-tions 42 have all been filled wi~h metal. The final form of the can wall is shown in ~igure 7b. It will be not~d that there is an appreciable thickness of metal indicated by the distance y between the points 41 and the inside 116 of the can wall which now rests firmly against the exterior wall Ç2 of the backing block 60. The indentations 42 are fully filled with metal of the wall, as shown by the dimension x. Generally speaking, where the height hl is rom .25 to .75 of the height h , a thickness of wall plus projections (dimensions y`plus x in Figure 7b) of from about 1.5 to 2.5 of the thickness of the original sheet metal can be obtained for sheet metals in the thickness range of about .Q7~ inch to 0~130 inch The relative size of dimensions y and x will of course depend on the size, shape and number of projectIons 42, and upon how close to the wall 62 and the roller ~0 is allowed ~o approach. In order to obtain a strong pulley for use in an automobile, the roller 40 is allowed to ap~roach the wall 62 only closely enough so that the minimum wall thick-ness 7 will be 0.040 inch. A smaller minimum thickness would of course be permissible if the pulley were designed for uses requiring less strength.
During the operation of Figure 7~ the backing block 60 is extremely important, as its walls 62 assists in distributing the metal o~ can wall 112 so that it fills all of the indentations 42.
After the roller 40 has come to the position of Figure 7b, it is removed, and the pulley can, which has now been fully for-med into a pulley suitable for use with a poly v-belt, is re-moved. It will be noted that the pulley thus formed has two flanges, 18 and 19, which give it considerable dimensional sta-bility, and has a series o~ grooves (the mirror image of pro-jections 41 and indentations 42 of the roller) for use with a poly v-belt.
An alternative arrangement, for use in making a pulley with a flat face! is shown in Figures 8a and 8b. Turning first to Figure 8a, a roller 70, rotating around an axis e-e which is parallel to axis a-a is shown.This roller has a flat face 71 -` ~a2~ 9 .
and two sloped portions 72 and 73. Portion 72 joins the flat face 71 to the top of the roller, whereas portion 73 joins the flat face to the bottom of the roller. The width of the face 71 is just slightly smaller than the width of the face 62 of backing block 60, and the slope o~ the sloped surfaces 72 and 73 are chosen having regard to the slopes of surface 26 and 25 with which they will co-act to form flanges.
The chucks 20 and 23 are caused to rotate simultaneously and in the same direction, carrying the can 20 with them. The axis e-e of the roller 70 is caused to move toward the axis a-a, with the roller oriented opposite the can as shown in Figure 8a.
The flat face 71 contacts the collapsed portion 112 of the can wall, pushing it against wali 62 of backing block 60. Simul-taneously, sloped surface 72 of roller 70 squeezes a ~ortion of the metal of the can wall against surface 26 of chuck 23, to form a flange, and surface 73 squeezes a portion of the metal of the can wall against sloped surface 25, also forming a flange.
Because of the bulged or partially collapsed surface of the wall of the canj there is more metal than would be needed merely to make a flat wall of the same thickness as the metal of the base.
Thus, when the roller 70 approaches the wall 62, a thick, smooth wall of metal 111 is formed, having smooth surfaces against faces 71 and 62. The advance o~ the roller 70 is stopped at a pre-determined place having regard to the amount of collapse which has been carried out in forming the buckled or collapsing wall 112, such that the newly formed wall 111 will be of a de-sired thickness. Generally, the thickness obtained will be somewhat in excess of the sheet ~etal forming the base 10 (ex-cluding any strengthening members or hubs) such as about from 3Q 1 1/4 to 2 times (preferably 1 1/3 to 1 1/2 times~ the thickness o~ the base 10. Obviously, if the roller 70 were advanced closer to the axis a-a, excess metal could squeeze out around the edges of the roller, leading to a thinner wall 111, but this would not be desirable, and does not form part o~ this invention. Having regard to the teachings herein a person skilled in the art can easily determine the amount of collapse required to give a suitable thickness 111, as h~ mav requireO
~Z~2~3~
If the flanges 18 and 19 have been preformed, as shown in Figures 4a and 4b, then the faces 72 and 73 will not in them-selves form flanges, but will merely mate smoothly against the pre-existing flanges 18 and 19, preventing metal from escaping from the area between face 62 and face 71, where the new, thicker wall 111 is being fcrmed.
After the condition shown in Figure 8b has been reached, the roller 70 is withdrawn, and the pulley can is removed from the chucks 20 and 23. A pulley can having a smooth, robust wall 111 has been formed, which is suitable as a pulley for a flat belt. The pulley also has flanges 18 and 19, which serve to retain the belt in place.
It will be noted that the steps of Figures 7 and $ each result intrinsically in a pulley having flanges 18 and 19.
Generally, it is preferred to retain these flanges, and one of the advantages of the invention is that the flange reduces the possibility o slippage of v-belts from pulleys formed according to the invention. However, it is possible, if desired, to remove the flanges 18 and 19 by means of a roller which nips off the flanges (as is known in the spun pulley art for removing un-wanted flanges or burrs) or by other conventional methods.
Therefore, although the flanges form a very desirable part of the invention, it is understood that unflanged pulleys also can be made by a process according to the invention.
If desired, instead of removing the pulley as formed with wall 111 from the chucks 20 and 23, the pulley can instead be subjected to the application of roller 40, as shown in Fig. 9, ~ollowing the steps shown in Figures 8a and ~b. The roller 40 approaches in a manner similar to that described with respect to Figures 7a and 7b, but, on this occasion, it engages flat, thick wall 111, rather than the bu-kled wall 112. However, the result obtained is the same as was obtained by the steps described in Figures 7a and 7b, as can be seen by comparing Figure 9 to Figure 7b.
In the foregoing disclosure, the contacting of the various rollers with the surface of the can wall has been accomplished by rotating the two chucks 20 and 23 at the same speed and in ~222~3~39 the same direction, entraining the can 15 along with them. The roller or rollers which then contact the surface of the can wall (such as, for example roller 40 or roller 70) axe freely rota-table, but are not powered. When they contact the can wall, they are caused to rotate by their contact with the rotating ca.n, at the same speed as the rotating can. It is of course within the scope of the invention to have the chucks 20 and 23 freely rotatable, and instead to power the roller which approa-ches the can wall. Alternately (although this is not preferred) both the roller and the chucks 20 and 23 could be powered so that both the can and the rolle~ are caused to rotate. The directions of rotation should preferably be such that, at the point of con-tact of the roller and the can, the two are moving in the same direction. However, they need not be moving at exactly the same speed, and, under`some circumstances, it is even possible to obtain good results with the can and the roller moving in dif-ferent directions, although this is not preferred.
Certain examples of the making of pulleys according to the disclosure given herein will no~ be given.
EXAMPLE I
: A can of the form shown in Figure 2 is dra~n by conventional means from sheet steel of thickness of 0.080 inches to have a width of 6.6 inches and a height h of 2.0 inches. The can is collapsed according to the step shown in Figure 5 to a height hl of 1.0 inch. The method steps with respect to Figure 7a and 7b are then performed on the can using a rollér 40 having six grooves spaced 0.140 inches from one another and having a depth of indentation 42 of 0.140 inches. The roller 40 is moved ~oward axis a-a ~ntil the distance between wall 62 and the projections 3Q 42 is 0.050 inches. When the roller 40 is removed and the can is removed from the chucks, it is found to be a well formed grooved pulley havi.ng two flanges (18 and 19 in the drawings) of approximately 6.6 inches in diameter and a central v-belt receiving portion having an average diameter of 6.0 inches and having six grooves corresponding to projections 41. ~ach of these grooves is 0.140 inches in depth, and the total depth of metal measured from the bottom of a vee to the inside of the . ,i ~L~2~
can (the distance y in Figure 7b) is 0.050 inches. The variation of depth between the six v-grooves is insi.gnificant, being less than .002 inches. The dimensions are substantiall~ constant around the diameter of a pulley.
EXA~PLE II
A sheet of sheet steel 0.080 inches in thickness is pre-formed into a can of the same shape as that described in Example I. The can is collapsed according to the step shown in Figure 5 to a height h1 of 1.0 inch. The steps illustrated in Figures 8a and 8b are carried out on the can. The roller 70 is allowed to approach the wall 60 such that the distance between face 71 and face 62 is 0.120 inches. When the roller 70 is withdrawn, and the can is removed from the chucks 20 and 22, it is found to have a v-belt receiving portion 6.0 inches in diameter and two flanges approximately 6.6 inches in diameter at each side of the v-belt receiving portion, The thickness of the wall of the v-belt re-ceiving portion is 0.120 inches, and the pulley is smoothly cy-lindrical in its v-belt receiving portion.
EXAMPLE III
_ _ . .
A pulley formed according to the teachings of Example II
is treated by a subsequent step as illustrated in Figure 9 and the associated disclosure. The roller 4~ is permitted to ap proach so that the projections 42 are a distance of 0.050 inches f`rom the face 62. When the roller is withdrawn and the can is removed from the chucks 20-and 23, a poly v-belt which is indis-tinguishable from the pulley formed in Example I is formed.
Each of the pulleys formed in Exampl~ I~ II and III is found to be highly resistant to being forced out of round, and is judged to be suitable for automotive and indeed heavy truck applications.
It is understood that the invention is not limited to the exact roller structure shown, nor to the exact pulley shapes illustrated, because the particular shapes of the rollers can be var;ed to provide other structural embodiments without de-parting from the scope of the present invention.
Having now described the features of the invention, andthe construction and operation of the preferred embodiments of - 18 ~
the novel method and th~ products provided by them, the inventor wishes it unde.rstood that the protection clai.med is not limited to the exact embodiments shown, but includes such modifications thereof as will be obvious to persons skilled in the art, and that the protection claimed is therefore limited only as set out in the appended claims.
Claims (11)
1. A poly v pulley formed from a pulley can blank of sheet metal of a predetermined minimum permissible thickness comprising:
a circular base of a thickness equal to said pre-determined minimum permissible thickness, and an integral annular wall portion having a generally smooth cylindrical interior peripheral surface and an exterior peripheral surface shaped to operatively engage a poly v-belt, said wall portion having a cross-sectional configuration which is defined by metal cold flow and which is straight along its interior periphery and has a plurality of v grooves in its exterior periphery, the distance between the trough of each v groove and said straight interior periphery being sufficient to provide required strength but less than the predetermined minimum thick-ness of said sheet metal can blank, the cross-sectional area of said wall portion being greater than the cross-sectional area of a section of said sheet metal can blank of said predetermined thickness having a length equal to the axial extent of said wall portion whereby said pulley contains less metal and weighs less than a pulley with a similarly configured wall portion made from a can blank of the same metal having a thickness such that a length thereof equal to the axial extent of said wall portion has a cross-sectional area equal to or slightly greater than the cross-sectional area of said wall portion.
a circular base of a thickness equal to said pre-determined minimum permissible thickness, and an integral annular wall portion having a generally smooth cylindrical interior peripheral surface and an exterior peripheral surface shaped to operatively engage a poly v-belt, said wall portion having a cross-sectional configuration which is defined by metal cold flow and which is straight along its interior periphery and has a plurality of v grooves in its exterior periphery, the distance between the trough of each v groove and said straight interior periphery being sufficient to provide required strength but less than the predetermined minimum thick-ness of said sheet metal can blank, the cross-sectional area of said wall portion being greater than the cross-sectional area of a section of said sheet metal can blank of said predetermined thickness having a length equal to the axial extent of said wall portion whereby said pulley contains less metal and weighs less than a pulley with a similarly configured wall portion made from a can blank of the same metal having a thickness such that a length thereof equal to the axial extent of said wall portion has a cross-sectional area equal to or slightly greater than the cross-sectional area of said wall portion.
2. A poly v pulley as defined in Claim 1 wherein said annular wall has formed integrally along opposite ends thereof a pair of flanges which extending radially and axially outwardly beyond the exterior periphery of said wall portion, one of said flanges being formed from an annular section of said can blank folded upon itself.
3. A poly v pulley as defined in Claim 1 or 2 wherein the cross-sectional area of said wall portion is greater than the cross-sectional area of a section of said sheet metal can blank of said predetermined thickness having a length equal to the axial extent of said wall portion by a factor of from 1 1/4 to 2.
4. A poly v pulley as defined in Claim 1 wherein the plurality of v-grooves define at least four annular projections each of which is of inverted v-shaped configuration, the perpen-dicular distance from said straight interior periphery to the crest of each annular projection being from 1.5 to 2.5 times said predetermined minimum thickness.
5. A poly v pulley as defined in Claim 1 or 2 wherein the cross-sectional area of said wall portion is greater than the cross-sectional area of a section of said sheet metal can blank of said predetermined thickness having a length equal to the axial extent of said wall portion by a factor of from 1 1/3 to 1 1/2.
6. A poly v pulley as defined in Claim 1, 2 or 4 wherein the distance between the trough of each v-groove and said straight interior periphery is at least 0.040 inches.
7. In a method of making a pulley from a pulley can blank of sheet metal of a predetermined minimum permissible thickness in which a circular base is formed from said pulley can blank with a thickness equal to said predetermined minimum permissible thickness, the improvement which comprises:
forming integral with said base a thickened annular wall portion from said pulley can blank, said wall portion having a thickness greater than said predetermined minimum thickness, and said thickened wall portion being formed by, partially collapsing an annular section of the pulley can blank having an axial extent greater than the axial extent of said annular wall portion to an axial extent equal to that of said annular wall portion without materially changing the thickness thereof but not collapsing such annular section completely such that interior surface portions thereof are interengaged, and moving the partially collapsed section of the pulley can blank radially inwardly while restraining the same against axial expansion and radially inward movement beyond a predetermined radial position so that the interior periphery surface area of said partially collapsed section is reduced without portions thereof interengaging.
forming integral with said base a thickened annular wall portion from said pulley can blank, said wall portion having a thickness greater than said predetermined minimum thickness, and said thickened wall portion being formed by, partially collapsing an annular section of the pulley can blank having an axial extent greater than the axial extent of said annular wall portion to an axial extent equal to that of said annular wall portion without materially changing the thickness thereof but not collapsing such annular section completely such that interior surface portions thereof are interengaged, and moving the partially collapsed section of the pulley can blank radially inwardly while restraining the same against axial expansion and radially inward movement beyond a predetermined radial position so that the interior periphery surface area of said partially collapsed section is reduced without portions thereof interengaging.
8. The improvement as defined in Claim 7 wherein the thickened annular wall portion after being formed by the steps aforesaid has a poly v-belt receiving configuration rolled in the exterior periphery thereof while the interior periphery thereof is supported in a straight axially extending configu-ration.
9. The improvement as defined in Claim 8 wherein prior to the moving step in the formation of said thickened annular wall portion, the can blank has a pair of flanges formed on opposite sides of said annular section which extend radially and axially outwardly of said thickened wall portion after the formation of the latter, one of said flanges being formed by folding upon itself another annular section of said pulley can blank adjacent said first mentioned annular section.
10. The improvement as defined in Claim 7, 8 or 9 wherein the thickness of said thickened annular wall portion is greater than said predetermined minimum permissible thickness by a factor of from 1 1/4 to 2.
11. The improvement as defined in Claim 7, 8 or 9 wherein the thickness of said thickened annular wall portion is greater than said predetermined minimum permissible thickness by a factor of from 1 1/3 to 1 1/2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000402458A CA1222889A (en) | 1977-12-16 | 1982-05-06 | Method of pulley manufacture and product |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA293,232A CA1094356A (en) | 1977-02-04 | 1977-12-16 | Method of pulley manufacture and product |
| CA368,331A CA1126541A (en) | 1977-12-16 | 1981-01-12 | Method of pulley manufacture and product |
| CA000402458A CA1222889A (en) | 1977-12-16 | 1982-05-06 | Method of pulley manufacture and product |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1222889A true CA1222889A (en) | 1987-06-16 |
Family
ID=25668612
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA368,331A Expired CA1126541A (en) | 1977-12-16 | 1981-01-12 | Method of pulley manufacture and product |
| CA000402458A Expired CA1222889A (en) | 1977-12-16 | 1982-05-06 | Method of pulley manufacture and product |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA368,331A Expired CA1126541A (en) | 1977-12-16 | 1981-01-12 | Method of pulley manufacture and product |
Country Status (1)
| Country | Link |
|---|---|
| CA (2) | CA1126541A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3816324A1 (en) * | 1987-07-07 | 1989-01-19 | Metzeler Gmbh | TORQUE DAMPER |
-
1981
- 1981-01-12 CA CA368,331A patent/CA1126541A/en not_active Expired
-
1982
- 1982-05-06 CA CA000402458A patent/CA1222889A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| CA1126541A (en) | 1982-06-29 |
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