GB1568675A

GB1568675A - Method and apparatus for making metal annular members

Info

Publication number: GB1568675A
Application number: GB4177176A
Authority: GB
Original assignee: General Tire and Rubber Co
Current assignee: Aerojet Rocketdyne Holdings Inc
Priority date: 1975-10-14
Filing date: 1976-10-07
Publication date: 1980-06-04
Also published as: AU1736276A; DE2646502C2; DE2646502A1; SE416895B; JPS626888B2; SE7906902L; BR7606866A; GB1568676A; FR2327831B1; JPS5249969A; ES461038A1; AU508952B2; SE7611447L; CA1059839A; ES450061A1; MX144067A; FR2327831A1

Description

(54) METHOD AND APPARATUS FOR MAKING METAL ANNULAR MEMBERS (71) We, THE GENERAL TIRE & RUB BER COMPANY, a corporation organized and existing under the laws of the State of Ohio, of One General Street, Akron, Ohio, United States of America, do hereby declare this invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to method and aw paratus for making a metal annular member, to a metal annular member produced by the process, or by means of the apparatus.

Suspension systems, particularly those suspcnsion 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 concentric annular members, usually of metal, separated by a rubber element of specific design which element is under compression. Such devices are sometimes called outer and inner metals or "outers" and "inners" and are more fully described in, for example, U.S. Patent Nos.

3,893,775; 3,495,859; and 3,199,186. The 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 U.S. patents 2,506,657 to Webster; 3,224,243 to VanDerberg; 3,789,650 to Axeloff; 3,263,477 to Roper; 2,930,483 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 slippage therebetween. One prior art procedure for 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 form of the surface texture be provided. and that this be accomplished inexpensively. Other prior art related to this feature are U.S.

patents 1,940,302 to Humphre; 1,959,256 to Zerk; 2,725,692 to Andreae; 2,819,105 to Belinke; 3,368,852 to Herbenar; and 3,504,513 to Black.

According to the present invention in one aspect, there is provided a process for making a metal annular member,-which comprises the steps of (a) placing an annular sheet metal blank between a driving punch and an external die, (b) forcing the annular blank into the external die by means of the driving punch so that the external die reduces the outside diameter of the blank over at least a portion of the axial length of the blank while the inside diameter of the blank at said portion is allowed to contact as dictated by the reduction of the outside diameter and without interference from the punch, this step of outside diameter reduction also causing one end of the blank to seat against a stop surface extending around the inside of the external die, and (c) driving the driving punch axially inside the annular blank and the external die thereby forming the blank into a desired annular member configuration as determined by the configuration of the driving punch and the external die and the said stop surface.

According to the invention in another aspect, there is provided forming apparatus for making a metal annular member which comprises: (a) an external die having a continuous die surface of the configuration desired for the external surface of at least part of the metal annular member, (b) means providing an inwardly project ing stop surface extending around the in side of the die at one axial end of said continuous die surface, (c) a driving punch mounted in relation to said external die for reciprocal travel along a path into and out of said external die, said driving punch having a first por tion of lesser diameter than the region of said die surface adjacent said stop surface and a second portion of larger diameter than said first portion, and (d) means for reciprocating said driving punch along said path, so that said first portion of the punch progresses within the continuous die surface towards said axial end thereof whereby an annular blank having an outside diameter greater than that of said region of said continuous sur face and a thickness less than the diameter difference between said region of the con tinuous die surface and the first portion of the punch is forced into the die by the punch until its leading end engages said stop surface so that a leading portion of the blank is reduced in diameter by the said region of the continuous die surface without interference by the punch.

By the invention metal annular members of precise tolerances can be made without the expenditure of an excessive amount of energy.

Embodiments of the invention will now be described by way of example with refer ence to the accompanying drawings, in which: Figure 1 is an axial section of an annular member produced by a method and appara tus embodying the present invention.

Figure 2 is an end elevation of the struc ture illustrated in Figure 1.

Figures 3 and 4 are views similar to Figure 1 of other types of annular members produced by embodiments of the pre sent invention.

Figure 5 is an enlarged section of a por tion of the structure illustrated in Figures 1, 3 and 4.

Figure 6 is a view similar to Figures 1, 3 and 4 of a metal blank used in a process embodying the present invention.

Figure 7 is an axial section through a forming apparatus embodying the present ention showing the final step in the pro making an annular member.

- - 7A is a fragmentary section taken line 7A-7A of Figure 7.

I is an enlarged fragmentary sec into I | o Figure 7 but with the work ed . lFiioved showing the structure of - --- --- 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 12-18 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, respectively, but showing an alternative form of the invention.

Figure 25 is a view similar to Figure 24 but showing still another alternative form of the invention.

Figure 26 is a schematic perspective view of a surface preparation procedure in the formation of blanks for use in the present invention.

Figures 27 and 28 are perspective views of annular members incorporating the surface treatment provided by the procedure of Figure 26.

Figure 29 is a fragmentary perspective view of an annular member 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, of Figure 26.

Figure 31 is an enlarged fragmentary cross-section of the rollers 201 of Figure 26 showing the surface configuration thereof.

Figure 32 is a schematic side elevation of a tube mill having a surface texturing device for the procedure of Figure 26 combined therewith.

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 4.

The annular member 20 includes a portion 25 of reduced diameter as described below a portion 26 of enlarged diameter as described below and a radially outwardly extending flange 27. Such annular members are used as a part of isolation bushings and must be formed to relatively precise tolerances. As an example, the annular member illustrated in Figure 1 has a length dimension tolerance 30 in one specific embodiment which ranges between 2 010 and 1990 inches. The following tolerances are also required of that specific embodiment of annular member: 31 02" min., 32 03-08", 33 43s470", 34 1-920-1-915", 35 1-853- 1 858", 36 1 732-1 742", 37 05" max.

radius 38 O5073", 39 1-792-1-802", and 40 2 3162 290a. 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 contiguration of the one end of the members of Figures 1, 3 and 4.

In order to manufacture these annular members 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 precision 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 specific embodiment 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 annular member in its final form.

Referring now to Figure 7, the structure of the forming apparatus is illustrated in detail as including a driving punch 55 and an external die 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 outwardly extending annular trap ledge 67 forming a part of the external 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 aproximately + 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 mentioned to make the press capable of handling six dies or (six parts) at a time when a lesser capacity press, i.e. 167 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. Also 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 the reformation of the OD at the reduced diameter portion. It is also intended that there be no extruding action in the manufacture of this annular member embodying the present invention.

Figures 8 and 9 are generally similar to Figure 7 but show the punch members 57A and 57B and the corresponding external dies as having a slightly different configuration.

It will be noted, however, that in Figures 8 and 9 the outwardly facing surfaces 57C and 57D of 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 operation of the structure of Figure 7 is shown serially.

Thus, in the process of the present invention the blank 45 of Figure 6 is positioned between the punch 55 and the external die 56. As shown in 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 O-ring 76 serves to maintain the blank 45 on the reduced diameter portion 90 of the punch in the event that the punch stops in mid stroke. In Figure 14 the next step is shown of the punch moving downwardly carrying the blank 45 into the die 56 until the lower end 100 of the blank 45 (see Figure 10) seats against a shoulder or ridge 101 formed on the external die member 71.

Note that the ridge 101 includes a radially extending horizontal surface 103 and a tapered surface 105. The tapered surface 105 is contiguous with the inwardly facing cylindrical surface 102 of the external die.

Tt 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 (Figure 10) which is engaged by the lower end 100 of the blank 45. The surfaces 105, 103, 101 and 106 provide a stop surface and serve to coin the lower end of the workpiece and to produce the lower end configuration 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 wherein the enlarged diameter portion 110 of the punch has been driven into the workpiece 45 so as to begin to form the enlarged diameter portion 26.

The punch 55 includes an annular outwardly extending surface 115 (Fig. 16) curving smoothly into a cylindrical 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 (Fig. 7), this trap ledge determining the outer diameter of the flange 27. The thus formed annular member is then ejected by raising of the punches 55 and 70 to the positions illustrated in Figure 18.

Referring now to Figures 19 and 22, an alternative preferred form of the invention is shown and is identical to the above described configuration and process of Figures 1, 2, 5, 6, 7, and 12-18 with one important difference being the forming of the lower end of the workpiece. The most difficult tolerances to meet in connection with the forming of 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 than in other portions of the workpiece. In certain applications of the annular members, 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 eertain situations has been found prefer able -because it assists in gripping a rubber or rubber-like sleeve of a shock absorbing unit.

In Figure 19 the ejector punch or knocl;- out 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. Also, 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 121) to the cylindrical inwardly tacing surface 121 of the external die 120. In the process for making the annular member of Figures 19 and 22, the lower end 122 of the blank is moved by the punch 125 into the external die reducing the outside diameter of the blank as described above; however, when the lower end of the blank is moved against the tapered surface 116, it is guided inwardly into the inwardly extending groove 112 which forms the stop surface thereby forming a tapered chamfer on the lower end of the blank. The groove 112 has an outwardly and downwardly extending surface 125' which cooperates with the surfaces 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, respectively, except that they all incorporate the changed process and apparatus for redirecting the lower end of the workpiece. While the specific construclion 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 of 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 145 and 146 and is not shown in Figures 7, 8 and 9. Also, the O-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' (Fig. 7) in the external die.

These vents permit 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, 20, 21 and 22 show a form of 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 generated or coined by the downward force of the tubular blank is approximately one-third of the metal thickness. If the apparatus of Figures 7-10 is used in an effort to produce a greater chamfer, the excessive force which is used may cause the blank to collapse inwardly in the area above the chamfer.

Therefore the alternate method of Figures 19, 20, 21, and 22 is provided to allow the chamfered end of the part to form inwardly creating a greater lead or chamfer effect but requiring a substantially reduced forming forct Figures 19, 20, 21 and 22 also clearly show the chamfered 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 force exerted at the end of 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 Ill. The slight stretching action 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 illustrate still further method and apparatus for providing a large chamfer or lead on the chamfered end of the outer or inner metal. The method and apparatus of Figure 23 does not require forcing the part off 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 as well as Figure 7) the shaded area 155 indicates the contact of the workpiece or blank with the punch 156 and the external die 157.

The shaded area extends around the flange 27, the enlarged diameter portion 26 and the outside of and 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 face 160 of the part. As described above in connection with Figure 7, the ID of the reduced diameter portion 25 is determined by the deformation of the OD at the reduced 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 through the -part. The oil t portion 161 prevents the lower end of the part from forming inward in an uncontrolled fashion4 and it is finally formed bv the fFusto-conical 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 frusto-conical surface 162.

During operation of the apparatus of Figures 23 and 24, the tapered surface 166 of the external die 157 acts to guide the lower end of the part inwardly, and as the pilot portion 161 travels downwardly it passes this inwardly deformed end of the part and acts as a stop that prevents further inward deformation of the lower end of the part. 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.

It can be seen that the apparatus of Figures 23 and 24 permits removal of the part from the dies without stretch ng of the chamfered end as required in the apparatus of Figures 19-22. Figures 25 shows another embodiment of the method and apparatus of this invention which permits even more extensive inward forming of the lower end of the part to the extent of permitting an inwardly directed flange 180 to be formed. The method and apparatus of Figure 25 are identical to that of Figures 23 and 24 with the exception that the ejector punch 181 has an annular projection 182 thereon which has an upper forming surface 183. Also the tapered surface 162 of 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 of a conventional reduction mill, the usual function of which is to reduce the thickness of sheet material 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 (Fig. 31) in the external surface thereof which are forced into the sheet metal 205 as the rollers rotate and the sheet metal moves through the rollers producing longitudinal projections 208 and grooves 206 respectively (Fig. 30) in the sheet metal 205. These longitudinal projections and grooves remain in the sheet metal as it is formed and welded into the tubular configuration 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 memhers 22 and 20 respectively, Prior to skelp ing 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 in a reduction mill the reduction in thickness of the sheet metal normally results in a lengthening rather than a widening thereof.

The rollers 201 in this specific embodiment 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 reduction mills, the rollers 201 can be incorporated into the design of the mill so that the rollers have a double function of reduction to a precise thickness as well as surface texturing.

Figure 30 shows the cross-sectional configuration of the sheet metal after it has passed between the rollers 201. The depth, width and configuration of the grooves may vary to provide the result desired; however, in one specific embodiment the grooves 206 are 060 inches in width and between 022 and 005 inches in depth and the projections are of the same width. Figure 31 shows in cross-section the die configuration used to produce the sheet metal surface configuration. This die configuration is constant in cross-section. It should be understood 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 the order of 50 Tons and can be calculated given the various parameters of the metal. Thus the structure which holds the rolls in a spaced relationship should be capable of resisting this force In some application it is desirable or necessary that the resistance to slippage between the metal sleeves and elastomeric insert be in both the rotary and axial directions in which 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 square 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 anpropriate cross-sectional representation for the rollers which produce the configuration of Figure 29.

Figure 32 shows in more detail a tube mill having surface treatment means of Figure 26. A standard uncoiler 225, which might be, for example, a Single Coil Cradle manMfactured bv McKay Division of Wean Iiidust,ries of Youngstown, Ohio, uncoils the sheet metal and feeds it into a standard stip sPlicer 226 and collector unit which nygRf( for example, an MPM strip joining shear welder made by the same company and including an accumulator 227.

The rollers 201 of Figure 26 are 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 frame 229. The surfaces of 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 waved lines, and/or a simulated phosphated surface. The structure 228-231 will 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 reduction mill is a Fenn Rolling Mill manufactured and sold by Fenn Manufacturing Company of Newington, Connecticut.

The large loop 235 of sheet metal is used to control the relative speed of the driven roll 230 and the tube mill 236. Two electric eyes, not shown, are located one above and one below the loop 235 and function to slow

Claims

**WARNING** start of CLMS field may overlap end of DESC **. hand, even in a reduction mill the reduction in thickness of the sheet metal normally results in a lengthening rather than a widening thereof. The rollers 201 in this specific embodiment 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 reduction mills, the rollers 201 can be incorporated into the design of the mill so that the rollers have a double function of reduction to a precise thickness as well as surface texturing. Figure 30 shows the cross-sectional configuration of the sheet metal after it has passed between the rollers 201. The depth, width and configuration of the grooves may vary to provide the result desired; however, in one specific embodiment the grooves 206 are 060 inches in width and between 022 and 005 inches in depth and the projections are of the same width. Figure 31 shows in cross-section the die configuration used to produce the sheet metal surface configuration. This die configuration is constant in cross-section. It should be understood 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 the order of 50 Tons and can be calculated given the various parameters of the metal. Thus the structure which holds the rolls in a spaced relationship should be capable of resisting this force In some application it is desirable or necessary that the resistance to slippage between the metal sleeves and elastomeric insert be in both the rotary and axial directions in which 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 square 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 anpropriate cross-sectional representation for the rollers which produce the configuration of Figure 29. Figure 32 shows in more detail a tube mill having surface treatment means of Figure 26. A standard uncoiler 225, which might be, for example, a Single Coil Cradle manMfactured bv McKay Division of Wean Iiidust,ries of Youngstown, Ohio, uncoils the sheet metal and feeds it into a standard stip sPlicer 226 and collector unit which nygRf( for example, an MPM strip joining shear welder made by the same company and including an accumulator 227. The rollers 201 of Figure 26 are 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 frame 229. The surfaces of 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 waved lines, and/or a simulated phosphated surface. The structure 228-231 will 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 reduction mill is a Fenn Rolling Mill manufactured and sold by Fenn Manufacturing Company of Newington, Connecticut. The large loop 235 of sheet metal is used to control the relative speed of the driven roll 230 and the tube mill 236. Two electric eyes, not shown, are located one above and one below the loop 235 and function to slow down or speed up the roll 230. The tube mill 236 is, for example, a 400 series McKay Tube Mill with cut off also manufactured by McKay Division of Wean Industries. The function of the tube mill and welder is to gradually skelp the sheet metal until the opposite edges thereof meet whereupon they are welded together It will be evident from the above description that the present invention provides an improved method and apparatus for making metal annular member of precise tolerances and desired surface finish. While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the scope of the claims are desired to be prctected. Our copending application No. 14982/79 describes and claims the process of Figs. 26 to 32. WHAT WE CLAIM IS:

1. A process for making a metal annular member, which comprises the steps of (a) placing an annular sheet metal blank between a driving punch and an external die, (b) forcing the annular blank into the external die by means of the driving punch so that the external die reduces the outside diameter of the blank over at least a por

tion of the axial length of the blank while the inside diameter of the blank at said portion is allowed to contract as dictated by the reduction of the outside diameter and without interference from the punch, this step of outside diameter reduction also causing one end of the blank to seat against a stop surface extending around the inside of the external die, and (c) driving the driving punch axially inside the annular blank and the external die thereby forming the blank into a desired annular member configuration as determined by the configuration of the driving punch and the external die and the said stop surface.

2. The process of claim 1 wherein the said one end of the annular blank engages a pilot on the punch as the punch is driven axially inside the annular blank, the punch finally forming the said one end of the annular blank at the completion of step (c).

3. A process according to claim 1 additionally comprising the step, prior to said step (b), of locating an ejector punch inside the external die, said stop surface being formed at least partly by the ejector punch, the formed annular member being ejected from the external die by moving the ejector punch through the external die.

4. A process according to claim 1 wherein said stop surface is formed at least partly by an inwardly projecting shoulder of the external die.

5. A process according to claim 4 wherein the said shoulder of the external die is sloping as viewed in axial cross-section and has the effect of guiding the end of the blank during step (b) inwardly into an annular recess in the ejector punch thereby forming a chamfer on the end of the blank.

6. A process according to any one of claims 3 to 5 wherein said step (b) causes reduction of the outside diameter of the blank all along its length.

7. A process according to any one of claims 3 to 6 wherein the driving punch and external die are so shaped that, in the driving step (c) the other end portion of the blank is caused to curl outwardly so as to form an outwardly extending annular flange portion on the blank between the driving punch and the external die.

8. A process according to claim 7 wherein step (b) causes reduction of the blank diameter over only a portion of its length, another portion of its length being enlarged in diameter in step (c) by cooperation of a portion of the driving punch and the external die.

9. A process according to any one of claims 1 to 8 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, skelping the sheet metal, and connecting opposite edges thereof to form the annular sheet metal blank.

10. A process according to claim 9 wherein said rollers have a constant crosssection and are shaped so as to produce grooves in said sheet metal.

11. A process according to claim 9 wherein said rollers are shaped so as to produce a grid pattern in said sheet metal.

12. A process of making a metal annular member substantially as any herein described with reference to the accompanying drawings.

13. Forming apparatus for making a metal annular member from an annular sheet metal blank which comprises: (a) an external die having a continuous die surface of the configuration desired for the external surface of at least part of the metal annular member, (b) means providing an inwardly projecting stop surface extending around the inside of the die at one axial end of said continuous die surface, (c) a driving punch mounted in relation to said external die for reciprocal travel along a path into and out of said external die, said driving punch having a first portion of lesser diameter than the region of said die surface adjacent said stop surface and a second portion of larger diameter than said first portion, and (d) means for reciprocating said driving punch along said path, so that said first portion of the punch progresses within the continuous die surface towards said axial end thereof whereby an annular blank having an outside diameter greater than that of said region of said continuous surface and a thickness less than the diameter difference between said region of the continuous die surface and the first portion of the punch is forced into the die by the punch until its leading end engages said stop surface so that a leading portion of the blank is reduced in diameter by the said region of the continuous die surface without interference by the punch.

14. Apparatus according to claim 13 wherein said driving 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 stop surface to block further movement of said one end of the blank.

15. The forming apparatus of claim 14 wherein said driving 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 driving punch is in its endmost position.

16. Apparatus according to any one of claims 13 to 15 wherein said stop surface comprises a shoulder of the external die which is sloping as viewed in axial crosssection and is adapted for coining a chamfer on the end of the metal annular member.

17. Apparatus according to claim 13 additionally comprising: (e) an ejector punch mounted with relation to said external die for reciprocal travel between a first position wherein an end of the ejector punch provides at least part of said stop surface for the end of the blank and a second position wherein said ejector punch has moved through said external die to force the formed annular member therefrom, and (f) means for reciprocating said ejector punch.

18. Apparatus according to claim 17 wherein said stop surface is partly provided by a shoulder of the external die which is sloping as seen in axial cross-section and said ejector punch has an annular recess into which the said shoulder guides the end of the blank so as to form an in-turned end on the metal annular member.

19. Apparatus according to any one of claims 13 to 18 wherein said external die includes an annular outwardly extending trap ledge located at the mouth of the length of the die which shapes the blank, said driving punch including an outwardly 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 form an end portion of the blank against said annular trap ledge when said punch moves into its endmost position, thereby forming an outwardly extending flange on the blank.

20. Apparatus according to claim 19 wherein the driving punch includes a stencil surface located on said axially facing surface for cooperating with said trap ledge to place identifying indicia on the blank.

21. Apparatus according to any one of claims 13 to 20 additionally comprising: (g) a resilient O-ring, said driving 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 a blank on said punch by a friction grip.

22. Apparatus for forming a metal annular member substantially as any herein described with reference to and as shown in the accompanying drawings.

23. A metal annular member formed by a process according to any one of claims 1 to 12 or by means of apparatus according to any one of claims ms 13 to 22.