Necking Die With Floating Center Post

Abstract

This disclosure relates to a die assembly for changing the diameter of end portions of cylindrical members having at least one circumferential wall portion of an increased effective thickness. Basically the die assembly is formed of a ring member and a post member with one of the members being floatingly mounted relative to the other member to permit the members to position themselves in accordance with the circumferential position of the wall portion of an increased effective thickness, thereby providing for a tightening up of die clearances which permits keeping the metal of the member being reshaped under better control and eliminating wrinkles. The die assembly is particularly adapted for necking down end portions of can bodies having lap seams.

Description

THIS invention relates in general to new and useful improvements in die assemblies, and more particularly to a necking die having a floating center post.

Although the invention is useful in changing the cross section of all types of cylindrical members, the die assembly finds particular advantage in connection with the shaping of can bodies, particularly can bodies of the type having a lap seam.

It will be readily apparent that when it is desired to either increase or decrease the cross section of a cylindrical member of a uniform wall thickness, it is merely necessary to provide a die assembly which includes a ring member and a post and wherein the ring member and post are in fixed positions relative to one another with there being a uniform clearance between the ring member and the post member. However, when the cylindrical member has a circumferential wall portion of an increased effective thickness, either because the formation of a burr thereon or because the cylindrical member has a lap seam, the clearance between the members of the die assembly must be increased. Furthermore, inasmuch as the position of the increased thickness wall portion is a random one, it will be seen that the usual tendency is to provide for an increased clearance with the spacing between the ring member and the post member being such as though the entire wall of the cylindrical member were of the same thickness as that of the increased thickness wall portion. However, as will be readily apparent, the desired relationship between the die assembly and the cylindrical member being worked upon will exist only along the wall portion of increased thickness with the remainder of the wall of the cylindrical member being worked upon being loosely received between the ring member and the post member, thereby subjecting this other wall portion to wrinkling during the reshaping thereof.

In accordance with this invention, it is desired to provide normally tight die clearances to keep the metal under control and eliminate wrinkles during the reshaping of the cylindrical members. This has been accomplished by decreasing the total clearance between the ring member and the post member to the normal clearance for cylindrical members of uniform wall thickness plus the additional thickness of the wall portion of the cylindrical member and by making one of the members of the die assembly floating for relative shifting relative to the other member so that the die assembly, with the decreased clearances, will accommodate the cylindrical members irrespective of the circumferential positions of the wall portions thereof having increased thickness.

Another object of this invention is to provide a novel die assembly which includes a ring member and a post member and wherein one of the members is fixedly secured and the other of the members is mounted for floating movement, wherein the amount of floating movement is restricted whereby the die members are always positioned to initially receive the cylindrical members irrespective of the positions of the wall portions of increased effective thickness thereof, and wherein the floating die member is readily shiftable by the cylindrical member engaged therewith so as to eccentrically position the floating die member relative to the fixed die member in accordance with the position of the cylindrical member being worked upon.

WITH the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings:

IN THE DRAWINGS:

FIG. 1 is a vertical sectional view taken through a die assembly for necking down an end portion of a can body having a lap seam.

FIG. 2 is a horizontal sectional view taken along the line 2--2 of FIG. 1 and shows the relationship of the various components of the die assembly.

FIG. 3 is an enlarged fragmentary sectional view of that portion designated in FIG. 1 and shows specifically the relationship between the various components of the die assembly and the can body being worked upon, with the shiftable position of the floating post member being shown in phantom lines.

REFERRING now to the drawings in detail, it will be seen that there is illustrated in FIG. 1 the overall die assembly, the die assembly being generally identified by the numeral 5. The die assembly 5 is carried by a suitable support 6 which may be the head of a press. The support 6 is illustrated as being mounted for reciprocal vertical movement, although it may be fixed and the can body may be reciprocated vertically with respect thereto during a reshaping of the can body.

The die assembly 5 basically includes a die ring or ring member 7 which is suitably fixedly secured to the underside of the support 6, and a die post or post member 8 which is disposed generally in concentric relation with respect to the die ring 7, but which is floatingly mounted for radial shifting movement relative to both the support 6 and the ring 7. The post 8 is secured to the support 6 by means of a bolt which is generally identified by the numeral 9.

The die ring 7 has secured thereto, in a manner not shown, a guide ring 10. The guide ring 10 is provided with a primary bore 11 therethrough for effectively guiding the end portion of a cylindrical member, such as the can body 12, into engagement with the die ring 7 and the post 8 and provides support to prevent buckling of the sidewall of a can body during a necking in operation. The guide ring 11 also has a tapered entrance bore 13 for centering the can body 12 relative to the primary bore 11.

It is to be noted that the underside of the support 6 is provided with a large diameter socket 14 in which the ring die 7 is seated. The interfit between the ring die 7 and the socket 14 is such so as to assure the fixed position of the ring die 7.

The underside of the support 6 is also provided with a central socket 15. The socket 15 is recessed with respect to the socket 14 and has received therein a circular cross-sectional projection 16 formed on the upper end of the post 8. It is to be noted, however, that the diameter of the projection 16 is less than the diameter of the socket 15 so as to permit the radial floating or shifting of the post 8 relative to the support 6. It is preferred that the differential in diameters of the socket 15 and the projection 16 be substantially equal to the increased wall thickness of a circumferential portion of the cylindrical member being worked upon, as will be described in detail hereinafter. This permits the shifting of the post 8 relative to the die ring 7 in accordance with the position of the increased wall thickness of the cylindrical member, such as the can body 12, while at the same time assuring the relative central position of the post 8 to facilitate the reception of the post 8 within the end portion of the cylindrical member being worked upon.

At this time, it is pointed out that the bolt 9 includes a shank 17 having a threaded end portion 18 which is threadedly engaged in the support 6. The shank 17 is received in a central bore 19 formed in the post 8 with there being sufficient clearance between the bore 19 and the shank 17 to permit the necessary floating movement of the post 8. The bolt 9 also includes an enlarged head 20 which is engaged against the underside of the post 8 and eliminates excessive end float and possible corking of the post 8.

In view of the fact that the die assembly 5 is a necking down die, the forming surface of the die assembly 5 is on the die ring 7 with the forming surface being identified by the numeral 21 and being best shown in FIG. 3. As the end portion of the cylindrical member, such as the can body 12, is guided by the guide ring 10 into the die assembly 5, the extreme end thereof engages the tapered forming surface 21 of the die ring 7 and compresses the end portion of the cylindrical member inwardly and forces the same into the space between the die ring 7 and the post 8 with the metal of the cylindrical member being sufficiently worked so as to permanently deform the same to form on the cylindrical member an end portion 22 of a reduced diameter.

With particular reference to the construction of the can body 12, it is to be noted from FIGS. 2 and 3 that the can body 12 is provided with a lap side seam 23. The lap side seam 23 may be formed by welding, soldering or by means of an adhesive. In any event, the side seam 23 of the can body 12 will have a greater wall thickness than the wall thickness of the remainder of the can body. Accordingly, if there is to be a tight fit of the can body 12 with both the post 8 and the die ring 7, it will be necessary that the clearance between the post 8 and the die ring 7 be substantially equal to the normal clearance between the post and the die ring for receiving a can body of constant wall thickness, plus the increased thickness of the can body at the side seam 23. Since the post 8 is free to float, it is immaterial as to the circumferential position of the side seam 23. It is merely necessary that the post 8 be so centered relative to the die ring 7 whereby movement of the necked in end portion of the can body 12 in between the die ring 7 and the post 8 is assured. It is, therefore, preferred that the radial floating of the post 8 be limited to a point where it comes no closer to the die ring 7 than the normal wall thickness of the can body 12. Thus, the post 8 will automatically equalize the clearances by being centered by the force of the can body 12 being inserted.

It will be readily apparent from the foregoing that as the support 6 and the can body 12 are moved relative to one another, the can body 12 will be first engaged by the ring 10 and centered relative to the die ring 7. As the die assembly 5 and the can body 12 come into operative relation, the post 8 will freely be received in the large diameter end portion of the can body 12 prior to the necking down thereof by the die ring 7. After the end portion of the can body 12 is necked down by the die ring 7, it will contact the post 8 which will function to limit the necking down of the end portion of the can body and which will cooperate with the die ring 7 to provide both for uniformity of cross section of the necked down end portion 22 and the elimination of wrinkles therein, which wrinkles commonly occur during the reduction in cross section of a tubular member.

It is also pointed out at this time that a similar die assembly may be provided for simultaneously engaging the opposite end of the can body 12 so that both ends of the can body 12 may be simultaneously necked down. It is also to be understood that if it is so desired, the post 8 may be fixed and the die ring 7 may be floatingly mounted. Furthermore, it is to be understood that a die assembly similar to the die assembly 5, but with different dimensions may be provided for the purpose of increasing the diameter of an end portion of the can body.

At this time it is also pointed out that the invention is not limited to a die assembly for receiving a cylindrical member having a lapped side seam. The die assembly 5 may also be utilized in conjunction with cylindrical members having burrs or other deformations at the extreme ends thereof which will prevent the normal freedom of movement of the end portion in between the die ring 7 and the post 8. Although only a preferred embodiment of the die assembly has been specifically illustrated and described herein, it is to be understood that minor variations may be made in the die assembly without departing from the spirit and scope of the invention, as defined by the appended claims.

Claims

We claim:

1. A die assembly for necking-in an end portion of a cylindrical member to define a cylindrical end portion of reduced diameter, said die assembly comprising a ring member for effecting the necking-in of a cylindrical member and a post member for limiting the necking-in effected by said ring member, said ring member having a bore of a diameter to receive a cylindrical member necked-in end portion and said post member being of a size to be received in a cylindrical member necked-in end portion, said die assembly being particularly adapted for use with cylindrical members having a circumferential wall portion of a greater thickness than other wall portions, and said die assembly including means for facilitating the reception of said thicker circumferential wall portion without orientation, said means including means mounting a selected one member of said ring member and said post member for limited radial floating movement relative to the other member of said ring member and said post member, the total clearance between said ring member bore and said post member being generally equal to the normal clearance for said die assembly plus the wall thickness increase of said thicker circumferential wall portion of tubular members which said die assembly is constructed.

2. The die assembly of claim 1 wherein said post member and said ring member are carried by a support, said one member being floatingly secured to said support and the other of said members being fixedly secured to said support, and cooperating means on said support and said one member limiting movement of said one member towards said other member to a distance generally equal to the wall thickness of a cylindrical member to be worked upon.

3. The die assembly of claim 2 wherein said cooperating means includes a cylindrical extension on said one member and a slightly larger cylindrical socket in said support receiving said cylindrical extension.

4. The die assembly of claim 1 wherein said die assembly is particularly adapted for reshaping can body end portions having lap seams, said ring member is fixed, and said post member is mounted for floating movement in accordance with the position of the lap seam of the can body being operated on by said die assembly.