US2909281A

US2909281A - Closed end sleeve-like boss and method of making

Info

Publication number: US2909281A
Application number: US430863A
Authority: US
Inventors: Olavi M Koskinen
Original assignee: Chrysler Corp
Current assignee: Old Carco LLC
Priority date: 1954-05-19
Filing date: 1954-05-19
Publication date: 1959-10-20
Anticipated expiration: 1976-10-20

Description

Oct. 20, 1959 o. M. KosKlNEN 25,909,28E

CLOSED END SLEEVE-'LIKE BOSS AND METHOD OF MAKING Filed May 19, 1954 2 Sheets-Sheet 1 M @L @i Oct. 20, 1959 O. M. KOSKINEN CLOSED END SLEEVE-LIKE BOSS AND METHOD OF MAKING Filed May 19, 1954 2 Sheets-Sheet 2 IN V EN TOR. 02m/z /fas 71627.

United States Patent() A'2,9"'0'9,`2"fi1 CLosED END SLEEVE-LIKE :Boss METHOD EoF MAKING olagvi M. Koskincn, handlichem, Mich., assigner to Chrysler Corporation, Highland Park, Mich., a coi'poration of Delaware j l Application May r19, 1954, serial No. 430,863

z claims. l(ci. 207-6) This invention relates to 'sleeve-like bosses that have knock-out integrally formed plugs 'that are removable 's'o that the bosses 'may receive bolts or Athe like, and to the method of forming su'ch bosses.

It is a primary object 'of this invention to provide a closed end, sleeve-like bo's's 'on which 'the 'end 'closure portion can be readily knocked ou't and the boss internally threaded to provide a s'ati'sfaetory bolt receiving formatio'n.

Itis another object of this invention to provide a sleevelike boss in which its 'method o'f forming work harden's the material forming' the boss and 'thus improves its texture for machining, wearability, andthe like.

It is still another object of this invention 'to provide a boss forming method that will provide 'relatively deep, symmetrical, sturdy, Work-hardened bosses in relatively thin sheet stock.

It is still another object of this invention to 'provide a boss formation of suitable dep'th to provide a satisfactory bolt receiving bore wherein the boss formed is of e depth considerably greater than the thickness of 4the stock from which 'theboss is extruded.

It is still another object 'of vthis vinvention lto provide a closed end sleeve-like boss formation that 'can be readily forned relatively 'thin fs'heet st ock'without 'perforating the stock yet one in which the closed 'end .portion of the boss formation may he readily removed b'y a knockout operation that `will not injure 'the adjacent sleeve portions ofthe boss. t

It is 'also an object of this invention t'o provide an iniproved type of die 'for forming Closed end, 'sleevetype bosses.-

lIt is still another object of this invention to provide an improved type of boss forniin'g extrusion process.

yOther 'objects' and advantages of 'this Yinvention will become readily 'apparent frori 'a readingof 'the following description and a consideration of 'the 'related drawings wherein: i

Fig. l is a fragmentary 'sectional elevational view of a punch 'type extrusion die used 'to for'r'n 'a boss embodying this invention, this view showing `the beginning of the boss forming operation;

Fig. 2 is a v'ie'w similar 'to Fig'. l 'but showing the boss forming operation at 'a second stage;

Fig. '3 is 'a view `similar to Figs. 1 and "2 but showing the boss 'forming operation ata third stage;

Fig. 4 is `a view sirnila'r t'o Figs. l-3 but showing vthe completion of 'the boss 'forming operation; Fig. 5 is 'a 'sec'tion'al elevational View of a modified form ofboss 'forming die having means associated with the'pll'nches 'for C'Oh't'rolli'g 4the .extrusion height 0i' depth ofthe boss;

Fig. v6 is an enlarged fragin'entafv sectional elevational vicvv of a hossjfoiination of l"the type formed `by "the `apparatus shown in 1-4';

Fig. 7 is a sectional elevational view of another Vrhodilied form of extrusion die apparatus wherein only an 'upper punch V and die block are utilized;

ICC

Fig. 8 is a fragmehtaryelevational view of an engine compartment 'lire 'vv'all having a plurality of compression extrusion formed closed end bos'ses 'formed therein;

fPig. '9 'is "a sectional elevational View taken along the' line 9 9 of Fig. 8; and

Fig. l0 is' a sectional elevational view of a portion of a fluid coupling casing 'formed withcompression extrusion type, closed end, bosses i'n one of 'which a Vsealing plug has been mounted.

It has been Acommon practice 'to punch a hole in a plate 'and to then thread the walls of the opening so as to provide a threaded recess to receive 'a bolt. This 'practice has' been suitable for relatively 'thickplates but it is highly unsatisfactory for relatively 'thin plates because of the inadequate 'thread area that is provided.

In anatteinpt to provide additional stock thickness around "the area Awhere the plate is punched, attempts have been iliade -to extrude or stretch the material removed from the punched out a'r'ea into a collar or sleeve extending around vvthe hole periphery. This has provided additional collar material around the punched out opening but this stretched inater'ial 'forming the hole collar has been stressed to s uch a degree during the 'punch-out process that it us'ually fractures 'at certain points around 'the collar-.periphery or, i'n the alternative, becomes so brittle that it cannot be properly machined during a thread forming operation.

The boss forming method herein disclosed redistributes the material `acted on in the punch 'out area so that a sturdy, thick, symmetrical, collar is formed around the p unc'h indented area. Furthermore, in the process of redistributin'g the stock material the material is Workhardened so that 'it is strengthened and improved as regards 'machinability and wearability. rThis method thus provides increased collar or boss 'depth 'for threading or bearing purposes Iand also f'gives an improved Vcollar material that is stronger and more readily machined. In addition, it be noted that 'this 'method initially provides a'close'd -exidLSleeve-type boss with a relatively thin knock-outplug rather than a completely pierced plate. This is quite important 'for 'there are many applications 'Where an imperiorate plate is initially desired but one that may be readily pierced at one or more locations, subsequent toits 'fabncation, 'to pifovide an opening for receiving `a bolt `or the like. Several s pecic applications of such 'platesare subsequently 'described in referring `t'o 'Figs rSell) fof thefdrawings. By providing a plate that will 'completely seal oil a'n area yet 'one that can be readily pierced by a simple knock-out operation, an important improvement has been achieved particularly when the knock-'out Voperation leaves an opening surrounded by a sturdy, symmetrical'collarof a "depth considerably greater than the plate thickness.

In `iigs. "114 of 'the drawings lll represents the upper extruding punch that extends through an yopening v11 'in the stripper plate l2. l is the work piece or plate that is of a thickness 't. AThe plate P is adapted to be supported 'on adie block i3 that has a 'stepped cylindrical bore `-or cavity le extending therethrough. Mounted -in the cavity 'lil "of the die 13 is 4'a lower extruding punch 16. lgower punch 16 may be reciprocably mounted in the die bore lil, 'as shown, for it can be rigidly associated with 'the die block l3.` ln the Vdisclosed form the lower punch lo is free to move vertically downward a limited :amount because it is 'supported on a compression V'spring I3 that normally urges it upwardly yoit" 'the die block seat `2l). When -a downwardly ldirected Aforce is applied to 'the upper end of 'the lower Ipunch z1'6 then the 'base a of the lower punch V`16 compresses t'he spring 18 and the lower 'pu'nch :1"6 seats on the Idie :block seat portion '20 as shown Ain :"Fi'gs. '2 and 2i.

The several 1steps 'or stages in 1the iformation of the iurthe lower punch head 1Gb is pressed into engagement with,

the underside of the plate P.

As a downwardly directed force is applied to the upper punch 10, see Fig. 2, the head b of the upper punch 10 is forced into and depresses the portions of the plate P overlying the die cavity 14 and causes the lower punch 16 to move downwardly and seat on the die block seat portion 20. During this initial downward movement of the upper punch 10, the portion 2S of the plate P, located in the pressure area between the upper and lower punch heads 10b, 16b respectively, are rst depressed a distance of approximately 1/3 the thickness t ofthe stock P and then these portions of plate P are compressed and squeezed radially outwardly to begin the formation of the sleevelike boss portions 30 by compressive extrusion.

As the downwardly directed force applied to the upper punch 10 is increased, see Fig. 3, upper punch 10 continues to compress and squeeze out the portions 25 of the plate P located in the pressure area between the punch heads 10b, 16b so that the plate portion 25 becomes progressively thinner while the compressed plate material squeezed from the plate portion 2S is entrapped in the die cavity 14 and redistributed in the peripheral area around the sides of the punch head 10b to form the sleevelike boss formation 30. It will be noted from Figs. 3 and 4 that the increased punch applying forces, which cause compressive extrusion of the sleeve-like boss portions 30, also develop reaction forces which cause the plate P to rise up off the top of the die block 13. The space between the top of die block 13 and the plate P has been denoted by the reference numeral r in Figs.

end boss 30 will now be de- In Fig. l the several cooperating parts of the 4 pression extrusion of the boss formations. In this manner the height or depth of the extruded boss 60 may be controlled while still providing for substantially the same upper punch penetration x beneath the top of the die block 13 before initiation of the compressive extrusion. The concavity of the punch end faces also provides a knockout plug 55 that has a thin outer periphery and a thick center andthis makes the plug 55 easier to knock out.

Fig. 6 shows an enlarged view of a portion of a plate P having a closed end boss 30 formed therein according to the teachings of Figs. 1-4. Material of the boss 30 that has been work hardened during its process of formation has been labeled to indicate a hardness of 100 Rockwell D whereasthe plate P from which the boss 30 was formed initially had a hardness of only 55 Rockwell D. It will also be noticed that the radius of curvature c at the base of the boss 30 is relatively Ilarge and this prevents an undesirable stress concentration at .this portion of the boss and adds to its strength.

Fig. 7 is a view of another type of extrusion die apparatus similar to that shown in Figs. 1-4. In this case, how-V ever, the lower punch 16 is completely omitted. This type of die is suitable for certain types of boss formations but does not give the accuracy obtainable with the die apparatus shown in Figs. l-4. The Figs. 1 4 apparatus seems more proficient in maintaining the centered position of the upper punch 10 with respect to the die block opening 14 so as to prevent cocking or tilting of the upper punch 10 with respect to the plate P and the die cavity 14a substantially the full depth of the cavity but leaves 3 and 4 and it is apparent from Figs. 3 and 4 that this reaction space r becomes progressively greater as the extrusion forces increase.

In applying this compressive extrusion process of boss formation to plates of several dilferent thicknesses, it has been found that an excellent boss formation is achieved when (see Fig. 4) the depth of penetration x of the upper punch head 10b below the top of the die block 13, before compressive extrusion of the metal begins, is substantially one-third (16) the thickness t of the plate stock P. It is to be realized that this particular relationship is not critical but one that is merely recommended. Obviously this relationship will vary somewhat with the variations in plate thickness, boss diameter and height and material quality and hardness.

As previously pointed out one of the prime advantages of this invention over the prior art is the work hardening of the boss material during boss formation due to the compression extrusion of the boss material. This is a very definite improvement over the well known punch type of boss forming process wherein the plate material is stretched to boss form and tensile stresses are set up in the boss material rather than compressive stresses as with this process. It has been found that in forming bosses according to this process from plate material of :iig inch -thickness and 55 Rockwell D hardness that this compression extrusion process will provide a boss of about 5%;

inch height or depth and that the hardness of the boss formation will have increased to about 100 Rockwell D (see Fig. 6).

In Fig. 5 is shown a modified form of boss forming extrusion die apparatus that is quite similar to the form of apparatus shown in Figs. 1-4 but differs therefrom in that the faces 50c and 46c of the upper and lower punches 50 and 46 respectively are each concavely dished. This dishing of the faces 46c, 50c of punch heads 46b, 50b provides an increased area between the punch heads into' which the plate material may be squeezed during the coma thin'space between its end face 10c and the bottom of the cavity 14a. This space provides for the thin knockout plug 25a that seals oi the end of the sleeve-like boss 70. As with the forms of die apparatus shown in Figs. 1-5, this form of device also work-hardens the boss material due to the compression of the boss material during formation thereof.

Figs. 8 and 9 show a portion of a vehicle engine compartment fire wall having a plurality of closed end sleevetype bosses 30 formed therein. In this case two of the bosses have had their knock-out plugs 25 removed and an accessory A has been bolted in these two open ended bosses by means of self tapping bolts 36. If at some later time additional accessories should be required, then the knock-out plugs 25 in some of the other bosses 30 could be removed. In the mean time the integral plugs 25 provide an air tight seal between opposite sides of the re wall D. It will also be noted that the bosses 30 formed by this compression extrusion process do not have sharp edges so they are suitable for ports for electrical wiring without the use of special wire supporting bushings to prevent cutting or wear of the wire insulating casings.

Fig. 10 shows the application of this compression method of boss extrusion to the casing of a fluid coupling. In this case one of the knock-out plugs 25 has been removed and a tapered screw plug 38 has been threaded into the open ended boss 30. While only a few examples of the utility of this type of boss formation have been shown, it is thought to be obvious that vehicle door hinge plates and pulley hubs and innumerable other parts of a motor vehicle could have this invention applied thereto. The applications of this invention to industries other than the motor vehicle industry are too numerous to even mention. Due to this invention permitting the use of thinner sheet stock while giving increased thickness of boss formations, considerable weight and cost savings can be achieved and for that reason this invention will be of considerable importance in the aircraft industry.

I claim:

1. The method of forming a relatively thick walled, sleeve-type, closed end, boss in a relatively thin sheet of material comprising depressing a circular area therein to form a concavity in said sheet until the underside of the depressed area lies below the general plane of the underside of the sheet material a distance approximately one-third the thickness of said sheet, thereafter continuously and progressively compressing the center portion of the depressed area of said concavity by applying pressure to the opposed inner and outer bottom sides of said depressed center portion without bodily displacing said center portion to subject the intervening material to a squeeze action thereby extruding the material thereof in directions transversely of the compressing force and entrapping said extruding material coupled with redistribution thereof in all directions parallel to the direction of the compressing force to form a thick walled, sleevetype, boss, closed by the remaining material of said squeezed central portion.

2. The method of forming a relatively thick walled, sleeve-type, closed end, boss in a relatively thin sheet of metal comprising depressing an annular area therein to form a concavity in said sheet until the underside of the depressed area lies below the general plane of the underside of the metal sheet a distance approximately one-third the thickness of said sheet, thereafter continuously and progressively compressing portions of the bottom of said depressed area of said concavity by applying pressure to the opposed concave and convex sides of said depressed bottom portion without bodily displacing said depressed bottom portion to subject the intervening metal to a squeeze action thereby extruding the metal thereof n directions transversely of the compressing force and entrapping said extruding metal at the outer periphery of said depressed bottom portion coupled with redistribution of the entrapped extruding metal in all directions parallel to the direction of the compressing force to form a thick walled, sleeve-type, boss, closed by the remaining metal of said squeezed portion.

References Cited in the file of this patent UNITED STATES PATENTS 64,197 Clark Apr. 30, 1867 1,082,200 Knaebel Dec. 23, 1913 1,270,059 Schaefer June 18, 1918 1,314,036 Amberg Aug. 26, 1919 1,408,917 Wilcox Mar. 7, 1922 2,016,296 Rossborough Oct. 8, 1935 2,051,639 Kalmbacker Aug. 18, 1936 2,213,812 Harper Sept. 3, 1940 2,451,511 Rice Oct. 19, 1948 2,627,652 Schweller Feb. 10, 1953 2,697,953 Chapman Dec. 28, 1954 FOREIGN PATENTS 12,137 Great Britain Oct. 12, 1885 21,053 Great Britain Nov. 21, 1900 725,881 Germany Oct. 1, 1942 France Nov. 8, 1950