CA1059839A - Process and apparatus for making metal outers and inners - Google Patents

Abstract

ABSTRACT
Process and apparatus for making a metal annular member of pre-cise tolerances and desired surface finish. An external die has a continuous die surface of the configuration desired for the ex-ternal surface of the metal annular member and an annular ridge sur-rounding the inside of the die for seating one end of an annular sheet metal blank. A first punch engages the sheet metal blank and drives it into the external die so as to reduce the external diameter of the blank and seat it against the ridge. The precise tolerance of the die surface of the external die determines both the external and at least a portion of the internal dimensions pro-duced in the annular sheet metal blank. The first punch is axially movable to an endmost position wherein substantially all of the blank has been forced into the die. An ejector punch is positioned inside of the external die and operates to provide a portion of the forming die surfaces as well as to eject the completed workpiece.

Description

~59~39 l~ls invention relates to a n~ethod and apparatus for making a metal annular member of precise tolerances and also to a method for providing desired surace finish.
Suspension systems, particularly those suspension systems found in automotive applications, make substantial use of devices commonly known as bushings. Generally these bushings consist of at least two more or less con-centric annular members, usually of metal, separated by a rubber element of specific design which element is under compression. Such devices are some-times called outer and inner metals or "outers" and "inners" and are more fully described in, for example, United States Patent Nos. 3,893,775;
3,495,859; and 3,199,186. lhe present procedure for making these annular members involves several draw die steps wherein an initially flat blank is drawn in successive draw die procedures into the desired configuration. This procedure is not entirely satisfactory because it is expensive, requiring repeated transfer steps, and it produces a product not always as accurate as desired. The relevant prior art may also include the United States Patents

2,506,657 to Webster; 3,224,243 to VanDerberg; 3,789,650 to Axeloff; 3,263, 477 to Roper; 2,930,~83 to Kaul; 3,314,278 to Bergman; 3,668,918 to Benteler;
and 3,740,993 to Moore.
In certain bushings it is desirable or necessary that the surface ` `
of the outer or inner which contacts the rubber element be so configured or finished as to grip the rubber element so as to eliminate or reduce slip-page therebetween. One prior art procedure or preventing relative movement ` between the metal sleeves and the elastomeric insert is disclosed in Sievers -patent 3,893~775 and involves sandblasting the surfaces of the metal sleeves and thereafter forming a phosphate coating thereon. It is desirable that `~
improved means be provided for forming a rough gripping surface on the metal sleeves of the bushing. It is desirable that better control over the precise orm of the surface texture be provided and that this be accomplished in-

3~ expensi~ely. Other prior art related to this eature are United States ..

.

3g Patents 1,940,302 -to ~lumphre; 1,~59,265 to ~erk; 2,725,692 to Andreae;
2,819,105 to ~elinke; 3,368,852 to ~lerbenar; and 3,50~,513 to Bl~ck.
According to one aspect of the present invention there is provided a process for making a metal annular member of precise tolerances which com-prises placing an annular sh0et metal blank between a punch and an external die, forcing the annular blank into the external die by means of the punch so that the external die reduces the outside diameter of the blank, maintain-ing said external die in continuous contact with the portion of said blank that is reduced in diameter, causing at least a portion of the inside dia-meter of the blank to contract as dictated by said reduction of the outside ;~
diameter and without interference with the punch, seating one end of the blank against a ridge surrounding the inside of the external die, and driving the punch axially inside the annular blank and the external die until the .~
punch seats against the other end of the blank thereby forming the blank ~ .
into the desired annular member configuration as determined by the configura- `
tion of the punch and the external die and the ridge thereon.
According to another aspect of the present invention there is provided apparatus for forming an annular shset metal blank into an annu-lar member of precise tolerances which comprises: `
;
~a) an external die having a continuous die surface of the configuration :, desired for the external surface of the annular member, at least one por~
tion of said continuous die surface being of smaller diameter than said ~ ~ .
annular metal blank so as to be capable of shrinking said blank to said ~ ~ `
smaller diameter when said blank is forced through said die, and said die .
having an annular ridge surrounding the inside of the die for seating one ~ .` `:
end of said annular metal blank, .
(b) a first punch mounted with relation to said external die for reci~
~, ~
procal travel through a path into and out of an endmost position within said . external die, said first punch being shaped and proportioned to fit inside . 3~ said annular metal blank and having a holding portion that engages and holds said blank so as to force said blank through said external die when said : ~ ~ 3 _ punch travels toward said endmost position, said first p~lch being spaced away from the portion of said annular metal blank that is reduced to a smaller diameter by the continuous die surface of said external die so as to allow the free inward movement of the internal surface of said annular metal blank when said external die reduces the diam~ter of the blank, and (c~ means for reciprocating said fi.rst punch axially through said path into and out of said endmost position in said external die.
Objects of the invention include the providing of an improved process and apparatus for making metal annular members of precise :~

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tolerances and the providing of a proc:ess and apparatus for making metal annular members of precise tolerances without the expendi~ure of an excessive amount of energy.
Figure 1 is an axial section of an annular member produced by the method and apparatus of the present invention.
Figure 2 is an end elevation of the structure illustrated in Figure 1.
Figures 3 and 4 are views similar to Figure l of other types of annular members produced by the present invention.
Figure 5 is an enlarged section of a portion of the structure illustrated in Figures 3 and 4.
Figure 6 is a view similar to Figures 1, 3 and 4 of a metal blank used in the process of the present invention.
Figure 7 is an axial section through the forming apparatus of the present invention showing the final step in the process of making an annular member.
Figure 7A is a fragmentary section taken along the line 7A-7A of , Figure 7.
Figure 7B is an enlarged fragmentary section similar to Figure 7 but with the workpiece removed showing the structure of Figure 7A.
Figures 8 and 9 are views similar to Figure 7 showing the final step in the forming process of making the alternative forms of annular members shown in Figures 3 and 4 respectively.
Figure 10 is an enlarged detailed sectional view of a portion of the structure illustrated in Figures 7, 8 and 9.
Figure 11 is an enlarged sectional detailed view of a portion of the structure illustrated in Figure 9.
Figures 12-1~ are somewhat schematic views of the structure ,~ illustrated in Figure 7 showing serial steps in the process of making an annular member Figures 19, 20, 21 and 22 are views similar to Figures 7, 8, 9 and 10, respectively, but showing alternative forms of the invention.
`- Figures 23 and 24 are views similar to Figures 19 and 20, respec-~ 59 ~ 3~

tively, but showing an alternative form of the invention.
Figure 25 is a view similar to Figure 24 but showing still another alternati~e form of the invention.
Figure 26 is a schematic perspective view of the surface prepara~ion procedure of the present invention.
Figures 27 and 28 are perspective views of annular members in-corporating the surface treatment of the present invention.
Figure 29 is a fragmentary perspective view of an annular mem-ber having an embossed grid configuration on its surface.
Figure 30 is an enlarged fragmentary cross section of the sheet metal 205 after it has passed through the rollers 201.
Figure 31 is an enlarged fragmentary cross section of the rollers 201 showing the surface configuration thereof.
Figure 32 is a schematic side elevation of a tube mill having the surface texturing device of the present invention combined therewith. ~::
For the purposes of promoting an tmderstanding of the principles of the invention, reference will now be made to the embodiment il-lustrated in the drawings and specific language will ~e used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and : such further applications of the prlnciples of the invention as ; illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
Referring more particularly to Figure 1, there is illustrated - a common type of annular member 20. Other annular members 21 and 22 are shown in Figures 3 and ~. The annular member 20 in-cludes a reduced diameter portion 25, an enlarged diameter portion 26 and a radially outwardly extending flange 27. Such annular mem-bers are used as a part of isolation bushings and must be formed to relatively precise tolerances. As an example, the annular member .

~L~359~3~

the annular member illustrated in Figure l has a length dimension tolerance 30 in one specific embodiment which ranges between 2 010 and 1.990 inches. The following tolerances are also required of that specific embodiment of annular member: 31 .02 min.", 32 .03-.08", 33 .430-.470", 34 1.920-1.915", 35 1.853-1.858", 36 1.732-1.742", 37 .OS" max, 3~ .055-.073", 39 1.792-1.802", and 40 2.310-2.290". The above dimensions are, of course, specific only to a particular embodiment of an annular member but serve to indicate that such annular members are required to be manufactured according to precise tolerances. Similar such precise tolerances are required for the annular members of Figures 3 and 4. Figure 5 shows in detail the cross sectional end edge configuration of the outer me~als of Figures 1, 3 and ~.
In order to manufacture the annular member in accordance with the present invention, a cylindrical blank 45 (Figure 6) is provided which has an outside diameter 46 and a predetermined length 47 both somewhat greater than the outside diameter and length, respectively, desired for the final annular member. The blank 45 also has a pre-cision wall thickness 50. The blank is formed of welded tubing, that is, flat sheet material which is welded into a cylinder with the outer weld surface skived and the inner weld surface hot planished to nominal wall thickness. The welded tubing in the above described speicific embodimen~ is SAE 1010 commercial quality cold rolled steel.
It is desirable that the wall thickness 50 of the blank be precise, for example, to produce the specific embodiment described above, that it be within a range of .057"-.062" for the reason that the wall thickness, together with the deformation procedure effected upon the outer surface of the blank is what determines at least a portion of the ID of the blank in its final form.
Referring now to Figure 7, the structure of the forming apparatus is illustrated in detail as including a punch 55 and an external die ~ 59835~
56. Punch 55 includes two members 57 and 60 with the member 57 secured to the member 60 by means of the threaded member 61. It should be noted that a stencil member 65 has a lower stencil 66 which cooperates with the trap ledge 67 forming a part of the ex-ternal die 56 to produce an indentation 68 (Figure 2) which functions ~ as an identifying indicia on the flange 27 of the outer metal.
- In one specific embodiment of the invention, the stencil 66 projects .020" where the thickness of the flange is .060" whereby the resulting ; indentation is approximately 1/3 of the flange thickness.
The punch 55 is reciprocated by a suitable die press such as, for example, a 30 stroke-per-minute 100 ton capacity straight side mechanical press with a 10" stroke. The 100 ton capacity is men-tioned to make the press capable o~ handling six dies or (six parts) at a time when a lesser capacity press, i.e. 16.7 ton, would operate to make one part at a time. The external die 56 thus is held in position so that there can be reciprocation movement of the punch 55 relative to the external die 56. ~lso mounted for reciprocation within the external die 56 is an ejector and an end coining punch 70. The ejector punch 70 is formed of hardened tool steel. The punch member 57 as well as the die insert 71 which has thereon the - inner continuous die face 72 is formed of hardened ground and polished special treated high speed steel.
It should be noted that the punch member 57 has an externally opening recess 75 which receives an O-ring 76. The function of the O-ring 76 is to prevent the blank from falling off of the punch when the press is stopped in mid-cycle. In Figure 7, the shaded area 80 extending around the flange 27, the enlarged diameter portion 26 and at the outside of and bottom of the reduced diameter portion 25 indicates contact of the workpiece or blank with the punch and the die 55 and 56. Thus, there is no contact of the punch with the inside surface of the reduced diameter portion 25, and this ID is determined by t'ne deformation of the OD at the reduced diameter por-~059~33~
tion. It is ~lso inten~ed that the~e b~ no ex~rudillg action in the manufac-tura of the amlular member o the present invention. ~ 5 Figures 8 and 9 ar0 generally similar to Figure 7 but show the ; punch members 57A and 57B and the corresponding external dies as having a slightly dif:ferent configuration. It will be noted, howe~er, that in Figures 8 and 9 the outwardly facing surfaces 57C and 57D o the punch member 57A and 57B do not contact a greater portion of the internal surface of the annular member as compared to Figure 7. Thus, this relatively large portion ~ ;
of inner surface is determined by the shrinkage of the outer surface during the forming procedure, together with the precise wall thickness of the blank 45.
Referring now to the somewhat schematic Figures 12-18, the opera-tion of the structure of Figure 7 is shown serially. Thus, in the process ~ :
of the present invention, the blank 45 o Figure 6 is positioned between the punch 55 and the external die 56. As shown i.n Figure 13, the punch 55 moves downwardly into the blank 45 until the blank is received upon the reduced diameter portion 90 of the punch member 57. The 0-ring 76 serves to maintain the blank 45 on the reduced diameter portion 90 of the punch in the event the punch stops in mid stroke. In Figure 14 the next step is shown of the punch moving downwardly carrying the blank 45 lnto the die 56 until the lower end 100 of the blank 45 ~see Figure 10) seats against a ridge 101 formed on the extexnal die member 71. Note that the ridge 101 includes a radially extending horizontal surface 103 and a tapered surace 105. The tapered surface 105 is contiguous with the inwardly facing cylindrical surface 102 of the external die.
It will also be evident from Figure 14 that the ejector die 70 is at its lower end of travel relative to the external die 56. Note also that the ejector die has a ledge 106 CFigure 10) which ls engaged by the lower end 100 of the blank 45. The surfaces 105, 103, 101 and 106 serve to coin the lower end of the workpiece and to produce the lower end coniguration illustrated in Figure 10. The next step of the process is the continued downward movement of the punch 55 into the position illustrated in Figure 15 59~13~

wherein the enlarged dlameter portion 110 of the punch has becn driven lnto the workpiece 45 so as to bogin to orm the enlarged diameter portion 26 of the outer metal.
~he punch 55 includes an outwardly extending surface 115 curving smoothly into a downwardly extending surface 116. As the punch 55 continues its downward movement, it curls the upper end portion 117 of the blank 45 into the position illustrated in Figure 16 and the enlarged diameter portion 26 of the annular member is further formed. Figure 17 shows the punch at its bottom position fully seated against the outer die 56. It will be noted that the flange 27 has been fully formed by being trapped within the trap ledge 67, this trap ledge determining the outer diameter of the flange 27.
The thus formed annular member is then ejectad by raising of the punches 55 and 70 to the positions illustrated in Figu~e 18.
Referring now to Figures 19 and 22, an alternative preferred form of the invention is shown and is id~ntical to the above described configurat-ion and process of Figures 5, 6, 7, 11 and 12-18 with one important difer-ence being the orming of the lower end o the workpiece. The most difficult ~ `
tolerances to meet in connection with the forming o~ the annular member of Figure 1 relate to the chamfer 110! The reason for this is that the plastic deformation of the metal in the area of the chamfer is more radical tha~ in other portions of the workpiece. In certain appllcations of the annular mem-bers, i,e. automotive suspension bushings, the user is willing to give up a constant internal diameter in favor of an in-turned lower end of the outer as shown in Figures 19-22. This modified form in certain situations has been found preferable because it assists in gripping a rubber or rubber-like sleeve of a shock absorbing unit.
In Figure 19 the ejector punch or knockout pin 111 is formed with a radially inwardly extending groove 112 including a surface 114 which ~-~
extends inwardly relative to the vertical at an angle of 15 degrees. That is~ the angle 115~ is 15 degrees. A1SOJ the horizontal surface 103 of the ridge is eliminated and replaced with the tapering surface 116 which leads from the cylindrical inwardly facing surface 117 of the external die 120 to ., , , ~5~ 39 tho cylindrical inwardly facing surace 121 of the e~ternal die 120. In the process for making the annular member o Figures 19 and 22, the lower end 122 of the blank ls movod by the p~mch 125 into the external die reducing the outside diameter of the blank as described above; however, when the lower end of the blank ls moved against the ridge or tapered surface 116, it is guided inwardly into the inwardly extending groove 112 thereby forming a tapered chamfer on the lower end of the blank. The groove 112 has an ou~-wardly and downwardly extending surface 125' which cooperates with the sur-faces 114 and 116 to redirect the metal of lower end of the workpiece and to thereby form it without radical metal deformation. ~ -Figures 19, 20 and 21 correspond to Figures 7, 8 and 9, respec-tively, except that they all incorporate the changed process and apparatus for redirecting the lower end of the workpiece. While the specific construc-tion features of Figures 19, 20 and 21 are different in some respects, the purpose and function is generally the same. Thus, in Figures 9 and 11 the somewhat pointed or chamfered upper end 130 of the workpiece is produced entirely by the punch 57B, and this is also true o Figure 21. Also, the manner of limiting downward movement of the ejector punch 111, 140 and 141 is shown in Figures 19, 20 and 21 as involving abutting surfaces 1~5 and 1~6 and is not shown in Figures 7, 8 and 9. Also, the 0-rings 76 of Figures 7, 8 and 9 are not shown, although they may also be used in the embodiments of Figures 19, 20 and 21 for the same purpose. Another feature which is present in the embodiment of Figures 19, 20 and 21 but is not shown is lube vents 150 in the external die. These vents pe~mit the flow out of the external ~.
die of oil used to lubricate the inside of the external die. During the forming process such oil needs to escape in order to allow the external die to properly form the workpiece. The vents 150 are connected through a duct ~not shown) in the external die to atmosphere. -,~
Figures 19, 2~, 21 and 22 show a form o the invention wherein the lower end 122 of the blank requires a larger or more pronounced chamfer than can be generated by the apparatus illustrated in Figures 7, 8, 9 and 10. In the embodiments of Figures 7, 8, 9 and 10 the maximum chamfer that can be ,.

~OS983'9 genera~ed or cointed by the downward force of the tubular blank is approxi-mately one-third of the metal thickness. If the apparatus of Figures 7-10 is used in an effort to produc0 a greater chamfer, the excessive force which is used causes the blank to collapse inwardly in the area above the chamfer.
Therefore, the alternate me~hod o Figures 19, 20, 21 and 22 is provided to allow the chamfered end of the part to form inwardly creating a greater lead or chamer effect but requiring a substantially reduced forming force. Figures 19, 20, 21 and 22 also clearly show the chamered end of the ` part formed around the enlarged head 143 or end of the ejector punch 111, 140 or 141. The part is removed from the knockout pin by a orce exerted at the end o the forming cycle after the part has been ejected to the position of Figure 18, in other words, has been moved above the external die 120. At this time a mechanical ejector mechanism 150 shown schematically in Figure 18 moves in the direction of arrows 151 and knocks the part off of the ejector ~ punch 111. The slight stretching actlon required to remove the part from `, the ejector punch 111 does not exceed the elastic limit of the metal of the part and for this reason does not deform the part.
Figures 23 and 24 illustrated still urther method and apparatus for providing a large chamer or lead on the chamfered end o the outer or inner metal. The method and apparatus of Figure 23 does not require forcing the part of of the~enlarged head of the ejector punch as in Figures 19-22.
It should be noted that in the procedure of Figure 23 ~as well as Figure 19 `-I as well as F;gure 7) the shaded area 155 indicates the contact of the work-i piece or blank with the punch 156 and the external die 157. The shaded area extends around the flange 27, the enlarged diameter porkion 26 and the out-side of the bottom of the reduced diameter portion 25. However, in Figure 23, unlike Figures 7 and 19, the shaded area does not include the lower end 160 of the part. As described abo~e in connection with Figure 7, the ~D of the reduced diameter portion 25 is determined by the deformation of the OD at - 30 the reducsd diameter portion.
The structure and method of Figure 23 are identical to Figure 19 except that the punch is formed to have a pilot portion 161 which projects ; :

~ 59~1:39 through the part. Tho pllot portion 161 provents the lower end of ~he part from forming inward in an uncontrollod fashion, and lt isf~ly formed by the frustoconical surface 162 immediately above the pilot portion 161. As `
mentioned, the inside diameter of the part at the reduced portion 25 is slightly greater than the external diameter of the punch at 165 above the frustoconical surface 162.
During operatiDn of the apparatus of Figures 23 and 24J the tapered surface 166 of th~ external die 157 acts to guide the lower end of the par~
against the pilot portion 161 whlch acts as a stop while the forming process goes through the various serial steps corresponding to Figures 13-16. Final forming of the lower end of the part occurs when the punch 156 reaches the position of Figure 23 and the surface 162 engages and forms the inside of `
the lower end of the part, Of course, the surface 162 is stopped in its illustrated position by the meeting of the external die and ejector punch surfaces 170 and 171.
It can be seen that the apparatus of Figures 23 and 24 permits removal of the part from the dies without stretching o the chamfered end as required in the apparatus of Figures 19-22. Figure 25 shows another embodiment of the method and apparatus of this invention which permits even more extensive i~ward orming of the`lower end of the part to the extent o ~`
:
permitting an inwardly directcd flange 180 to be formed. The method and i`: apparatus o Figure 25 are identical to that of Figures 23 and 24 with the exGeption that the ejector punch 181 has an annular projection 182 thereon -~ which has an upper ormlng surace 183. Also the tapered surface 162 o punch 156 is replaced by the radially extending surface 185.
Referring to Figure 26, there is illustrated a coil 200 of sheet metal which is drawn through rollers 201 by suitable drive means ~not shown).
The rollers 201 and the drive means may be a part o a conventlonal reduction mill, the usual function of which is to reduce the thickness of sheet mater-ial down to a precise thickness. The rollers 201 may be a part of a tube mill which forms sheet into tube. The rollers 201 have longitudinal grooves 202 and projections 203 in the external surfaGe thereof which are forced into :

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~0~83'~
tho sh~t motal 205 as tho rollers rotate .~nd tho sheet metal moves through the rollers producing longitudinal grooves 206 and projections 208 in the sheet metal 205. These longitudinal grooves remain in the sheet metal as it ls formed and w~lded into a tubular coniguration 207 by a butted joint 210 and is then formed into the annular members 211 and 212 by the identical procedures described above with respect to annular members 20 and 22. Prior to curling the flat sheet 205 into the tubular configuration 207, it may be necessary to trim the edges of the sheet metal so that the tube has the proper diameter. On the other hand, even ~n a reduction mill the reduction in thick-ness of the sheet metal normally results in a lengthening ra~her than a widen-ing thereof.
The rollers 201 .in one specific embodiment of the invention are designed as an attachment or addition to operate on the sheet metal before it moves into an existing tube mill. In designing new tube mills or reduct-ion mills, the rollers 201 can be incorporated into the design o the mill so that the rollers have a double function o reduction to a precise thick-ness as well as surface texturing.
Figure 30 shows the cross sectional coniguration of the sheet metal : after it has passed between the rollers 201. The depth, width and configur-ation of the grooves may vary to provide the result desired; ho~ever, in one speclfic embodiment the grooves 206 are .060 inches in ~idth and between .002 and .005 inches in depth and the projections are of the sam0 width. Figure 31 shows in cross ~ection the~die coniguration used to produce the sheet metal surface configuration. This die configuration is constant in cross section. It should be unders~ood that the rolls 201 are fixed in a spaced relationship which is the thickness desired for the sheet metal 205. Because the sheet metal from the coil 200 is thicker than the spacing, a substantial force must be exerted on the sheet metal by the rolls 201 which might be, for example, in order of 50 Tons and can be calculated given the various paramet- ~;
ers o the mekal. Thus the structure which holds the rolls in a spaced relationship should be capable of resisting this force.
In some applications it is desirable or necessary that the resis-~ID5~33~ ~ `

tance to slippage between the metal sleeves and ela~tomeric insert be in both the rotary and axial dir0ctions in whlch case the surface configuration of Figure 29 is desirable. The sheet metal 215 has a pair of grids 216, one on each side, including a series of s~uare recesses 217 which are produced by rollers identical to 201 except that their external configuration is not constant in cross section but instead includes a series of projections of mating configuration to the surface of the sheet metal 215. Thus Figure 31 ; is also an appropriate cross sectional representation or the rollers which -produce the configuration of Figure 29.
Figure 32 shows in more detail a tube mill having the present -invention incorporated therein. A standard uncoiler 225, which might be, for example, a Single Coil Cradle manufactured by McKay ~ivislon of Wean Industries of Yo~mgstown, Ohio, uncoils the sheet metal and feeds it into a standard strip splicer 226 and collector unit which migh~ be, for example, a strip joining shear welder made by the same company and including an accumulator 227~ The rollers 201 ar0 represented in Figure 32 by rollers 230 and 231. The roller 230 is driven and rotatable, and its axis is fixed.
The roller 231 is vertically adjustable by the hydraulic motor 228, but its .
- axis can be fixed in a desired spaced relationship to the roller 230 by the fram~ 229. The surfaces o the rollers 230 and 231 have the appropriate configuration to produce the texturing desired 206 or 216 or any other ~` desired texturing such as, for example, annular lines, diagonal cross hatch ` or diamond design patterns, longitudinal parallel ~aved lines, and/or a simulated phosphated surface. The structure 228-231 ~ill not be described in greater detail because it is a standard cold reduction mill except for the -~ particular surface of the rollers 230 and 231. An example of such a cold .: .
reductlon mill is a Fenn Rolling Mill manufactured and sold by Fenn Manufact-uring Company of Ne-~ington, Connecticut.
The largG loop 2~5 of sheet metal is used to control the relative speed o the driven roll 230 and the tube mill 236. T~o electric e~es, not shown, are located one above and one below the loop 235 and function to slow down or speed up t~e roll 230. The tube mill 236 is, for example, a 400 1~59839 series.~lcKay Tube Mill ~ith cut of al~o manu~actured by Mc~ay Division of - Wean Industri~s. ~ho ~unction o~ the tube mill and welder is to gradually coil the sheet metal until the opposite edges thercof meet whereupon they are welded together.
It will b~ evident from the above description that the present invention provides an improved method and apparatus for making metal annular ....
members of precise tolerances and desired surface finish. While the invent-ion has been illustrated and described in detail in the drawin~ and foregoing description, the same is to be considered as illustrative and not restrictive in character, it bsing understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention and the scope of the claims are desired to be protected.
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Claims (22)

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

1. A process for making a metal annular member of precise tolerances which comprises placing an annular sheet metal blank between a punch and an external die, forcing the annular blank into the external die by means of the punch so that the external die reduces the outside diameter of the blank, maintaining said external die in continuous contact with the portion of said blank that is reduced in diameter, causing at least a portion of the inside diameter of the blank to contract as dictated by said reduction of the outside diameter and without interference with the punch, seating one end of the blank against a ridge surrounding the inside of the external die, and driving the punch axially inside the annular blank and the external die until the punch seats against the other end of the blank thereby forming the blank into the desired annular member configuration as determined by the configuration of the punch and the external die and the ridge thereon.

2. The process of claim 1 wherein the annular blank is forced into the external die until the one end of the blank engages a pilot on the punch, said one end being finally formed by said punch when the punch is driven into the annular blank.

3. The process of claim 1 additionally comprising the step, prior to said forcing step, of locating an ejector punch inside of the external die, said forcing step also seating one end of the blank against the ejector punch, said desired annular member configuration being determined by the con-figuration of the punches and the external die and the ridge thereon, and ejecting the thus formed annular member from the external die by moving the ejector punch through the external die.

4. The process of claim 1 additionally comprising the step, prior to said forcing step, of locating an ejector punch inside of the external die, said ridge being tapered, said forcing step also moving one end of the blank against said tapered ridge guiding the one end of the blank inwardly into an annular groove in the ejector punch thereby forming a tapered cham-fer on the one end of the blank, said desired annular member configuration being determined by the configuration of the punches and the external die.

5. Tile process of claim 1 additionally comprising the step, prior to said forcing step, of locating an ejector punch inside of the external die, said forcing step also seating one end of the blank against the ejector punch, said driving step also reducing the outside diameter of the blank all along its length, said desired annular member configuration being determined by the configuration of the punches and the external die and the ridge thereon, and ejecting the thus formed annular member from the external die by moving the ejector punch through the external die.

6. The process of claim 1 wherein the annular member includes an annu-lar flange extending outwardly from one end thereof, said process additionally comprising the step, prior to said forcing step, of locating an ejector punch inside of the external die, said forcing step also seating one and of the blank against the ejector punch, said driving step causing the end portion of the blank to curl outwardly, said first mentioned punch when seated against the other end of the blank containing said end portion between said first mentioned punch and said external die forming an outwardly extending annular flange on said member and ejecting the thus formed annular member from the external die by moving the ejector punch through the external die.

7. The process of claim 1 wherein the annular member includes a re-duced diameter portion, an enlarged diamater portion and an annular flange on said enlarged diameter portion, said process additionally comprising the step, prior to said forcing step, of locating an ejector punch inside of the exter-nal die, said forcing step also seating one end of the blank against the ejector punch and causing the external die to reduce the outside diameter of the blank at one area thereof forming the reduced diameter portion, said driving step causing an enlarged portion of the first mentioned punch to ex-pand a further area of the blank against the external die forming the enlarged diameter portion, further driving the first mentioned punch into the annular blank and the external die causing the end portion of the enlarged diameter portion to curl outwardly, said first mentioned punch when seated against the other end of the blank containing said and portion between said first mentioned punch and said external die forming an outwardly extending annular flange on said enlarged diameter portion, and ejecting the thus formed annular member from the external die by moving the ejector punch though the external die.

8. Apparatus for forming an annular sheet metal blank into an annular member of precise tolerances which comprises:
(a) an external die having a continuous die surface of the configuration desired for the external surface of the annular member, at least one portion of said continuous die surface being of smaller diameter than said annular metal blank so as to be capable of shrinking said blank to said smaller diameter when said blank is forced through said die, and said die having an annular ridge surrounding the inside of the die for seating one end of said annular metal blank, (b) a first punch mounted with relation to said external die for reci-procal travel through a path into and out of an endmost position within said external die, said first punch being shaped and proportioned to fit inside said annular metal blank and having a holding portion that engages and holds said blank so as to force said blank through said external die when said punch travels toward said endmost position, said first punch being spaced away from the portion of said annular metal blank that is reduced to a smaller diameter by the continuous die surface of said external die so as to allow the free inward movement of the internal surface of said annular metal blank when said external die reduces the diameter of the blank, and (c) means for reciprocating said first punch axially through said path into and out of said endmost position in said external die.

9. The forming apparatus of claim 8 wherein said first punch has a pilot mounted thereon, said pilot having pilot surfaces which extend and move parallel to said path and are adapted to cooperate with said annular ridge to block further movement of said one end of the blank.

10. The forming apparatus of claim 9 wherein said first punch has a forming surface thereon adjacent to said pilot, said forming surface being positioned to engage and finally form the one end of the annular sheet metal blank when said first punch is in said endmost position.

11. The forming apparatus of claim 8 wherein said external die includes an inwardly facing cylindrical surface and said ridge includes a tapered sur-face and a radially extending surface for coining a chamfer on the end of the metal annular member.

12. The forming apparatus of claim 8 additionally comprising:
(d) an ejector punch mounted with relation to said external die for reciprocal travel between a first position wherein said ejector punch is flush with said ridge and provides a further surface seating said annular sheet metal blank and a second position wherein said ejector punch has moved through said external die to force the formed annular member therefrom.
(e) and means for reciprocating said ejector punch.

13. The forming apparatus of claim 12 wherein said external die includes an inwardly facing cylindrical surface and said ridge includes a tapered surface, said ejector punch having an annular groove therein which is flush with said tapered surface and leads radially inwardly whereby said tapered surface and groove cooperate to form an in-turned end on the metal annular member.

14. The forming apparatus of claim 8 wherein said external die includes an annular trap ledge forming a part of said continuous surface and located at the mouth of said continuous surface, said first punch including an out-wardly facing surface and an axially facing surface contiguous with and curving smoothly into said outwardly facing surface, said axially facing surface being proportioned and arranged to engage the end portion of a blank received on said outwardly facing surface and to curl it outwardly as said punch moves through said path and to final form an end portion of the blank into said annular trap ledge when said punch moves into its endmost position.

15. The forming apparatus of claim 12 additionally comprising:
(f) a resilient O-ring, said punch having a recess within its outwardly facing surface with said O-ring being received in said recess and projecting outwardly of said outwardly facing surface for holding said annular metal blank on said punch.

16. The forming apparatus of claim 14 wherein said punch includes a stencil surface located on said axially facing surface for cooperating with said trap ledge to place identifying indicia on said workpiece.

17. The forming apparatus of claim 16 additionally comprising:
(d) an ejector punch mounted with relation to said external die for reciprocal travel between a first position wherein said ejector punch is flush with said ridge and provides a further surface seating said annular sheet metal blank and a second position wherein said ejector punch has moved through said external die to force the formed annular metal blank therefrom;
(e) and means for reciprocating said ejector punch.

18. The forming apparatus of claim 17 wherein said external die includes an inwardly facing cylindrical surface and said ridge includes a tapered sur-face, said ejector punch having an annular groove therein which is flush with said tapered surface and leads radially inwardly whereby said tapered surface and groove cooperate to form an in-turned end on the annular metal blank.

19. The process of claim 1 wherein said annular sheet metal blank is formed by the steps of moving flat sheet metal between two parallel rollers which are maintained in spaced relation to one another and rotate against the sheet metal as it moves therebetween to deform the surface of the sheet metal blank into a desired surface configuration, curling the sheet metal, and connecting opposite edges thereof to form the annular sheet metal blank.

20. The process of claim 19 wherein said rollers have a constant cross section and are configurated to do and produce grooves in said sheet metal.

21. The process of claim 19 wherein said rollers are configured to and do produce a grid in said sheet metal.

22. The forming apparatus of claim 8 wherein said external die has an enlarged portion located at the mouth end of said continuous surface, said enlarged portion of the die having a diameter large than said annular metal blank, and said first punch also has an enlarged portion arranged to push on the other end of said annular metal blank until said one end of said blank seats on said annular ridge, said enlarged portion of the first punch being shaped to expand said other end of said annular metal blank into engagement with said enlarged portion of said external die when said blank is seated on said annular ridge.