US2711772A

US2711772A - Tube clamping die

Info

Publication number: US2711772A
Application number: US379253A
Authority: US
Inventors: Frank R Wilson
Original assignee: Individual
Current assignee: Individual
Priority date: 1953-09-09
Filing date: 1953-09-09
Publication date: 1955-06-28
Anticipated expiration: 1972-06-28

Description

June 28, 1955 F. R. WILSON 2,711,772

TUBE CLAMPING DIE Filed Sept. 9, 1953 I lllL-Jllll I INVENTOR. v pl o FRANK R. WILSON BY DES JARDINS, ROBINSON 8. KEISER HIS ATTORNEYS atent Ofl ice Patented June 28, 1955 TUBE CLAMPING DIE Frank R. Wilson, Memphis, Tenn.

Application September 9, 1953, Serial No. 379,253

5 Claims. (Cl. 153-79) This invention relates to tube clamping dies for use with tube flaring tools, and more particularly, to an improvement in those types of clamping dies in which the clamping recesses are provided with chamfers at their upper edges to back up the flare on the tube as it is formed by the flaring cone.

It has heretofore been the practice in the construction of tube clamping dies for use with flaring cones of conventional design to provide a chamfer on the upper edge of each clamping recess to back up the flare on the tube as the flaring cone is forced into the end of the tube thereby facilitating the accurate shaping of the flare produced by the cone. In the past, it has been customary to make the taper of the chamfer correspond with the taper on the flaring cone, that is, in tools having a 45 flaring cone, the recesses of the clamping dies are provided with 45 chamfers. As a result, when the flaring cone is forced into the end of a tube held in the clamping die, a sharp corner is formed at the bottom of the flare where it joins the tube. A weakness is thereby introduced into the flared tube at the point where the flare joins the tube and cracking or splitting of the tube at this point is likely to occur, and complete separation or breaking off of the flare may result.

For the purpose of eliminating this source of weakness in the tube, 1 have found that it is helpful to make the angle of inclination of the chamfer from 5 to 10 less than that of the cone so that when the cone is forced into the tube, a clearance or relief will be provided at the bottom of the chamfer provided excessive axial force is not appliedto the cone. The formation of a sharp corner at the bottom of the flare will thereby be avoided since the corner formed by the intersection of the chamfer with the walls of the recess will not be forced into the wall of the tube at this point.

In order to more positively insure that no indentation of the tube will occur at the point where the flare joins the cylindrical portion of the tube and to cause a transition fillet portion to be formed between the cylindrical portion of the tube and the wall of the flare formed thereon, the bottom portion of the chamfer may be removed to provide a clearance or relief extending circumferentially around the base of the chamfer so as to prevent contact between the wall of the tube and the die. As hereinafter to be described, this relief may be pro- .vided by counterboring the upper end of the cylindrical portion of the recess so as to remove the corner formed by the intersection of the chamfer with the cylindrical portion of the recess. The diameter of the counterbore need be only slightly greater than the diameter of the clamping recess in order to provide the necessary clearance. By thus relieving the bottom of the chamfer, positive assurance is given that the sharp, bottom edge of the chamfer will not form a sharp corner at the bottom of the flare formed on the end of the tube. The corner formed by the intersection of the top of the counterbore with the bottom of the chamfer is preferably rounded to avoid indenting the tube at this location and, to the same end, the angle of inclination of the chamfer may be made less than that of the cone to relieve the pressure on the tube at the bottom of the chamfer. Also, to prevent any indenting of the wall of the flare by the corner formed at the intersection of the chamfer with the top face of the clamping die, this corner may be rounded slightly to prevent nicking or indenting of the flare at this point.

Accordingly, it is an object of my invention to so modify the shape and inclination of the chamfered surface as to prevent sharp corners or indentations being formed in the flared portion of the tube. Experience has shown that such sharp corners or indentations introdece a weakness in the tube and render it subject to splitting or cracking at this point while the tube is in service.

Another object of my invention is to provide a chamfer on the upper edge of the die opening which is inclined at a substantially steeper angle than the sides of the flaring cone so as to cause the location of maximum pressure of the cone on the tube to occur at the top of the chamfer.

Another object of my invention is to provide a counterbore in the lower part of the chamfer, which is of larger diameter than the clamping recess, so that the corner formed by the intersection of the chamfer and the recess is relieved and the formation of a sharp corner at the bottom of the flare is avoided.

Another object of my invention is to round the corner formed by the intersection of the chamfer with the top face of the die, and also to round the corner at the top of the counterbore to prevent annular grooves or indentations being formed in the outer surface of the flare at these locations. t

With these and other objects in view which will become apparent from the following description, the invention includes certain novel features of construction and combinations of elements, the essential features of which are set forth in the appended claims and a preferred form or embodiment of which will hereinafter be described with reference to the drawings which accompany and form a part of this specification.

In the drawings:

Fig. 1 is a side view of a tube flaring tool incorporating my invention.

Fig. 2 is a fragmentary view illustrating a conventional type of clamping die.

Fig. 3 is a fragmentary view illustrating a clamping die incorporating the teachings of my invention.

Fig. 4 is a fragmentary view of a clamping die incorporating still further teachings of my invention.

In Fig. 1 of the drawings there is shown a tube flaring tool having a flaring cone and advancing means therefor of conventional design. The tube to be flared, shown in phantom outline in Fig. 1 and indicated by reference numeral it), is held in a clamping die, indicated generally at 11, which is secured on the lower ends of the legs of a yoke 12. This die may be of the same general type as that shown and described in U. S. Patent No. 2,563,088, patented August 7, 1951, on an application filed by Karl W. Wilks, In, and Glenn W. Wolcott. That is, the clamp ing die may consist of two complementary die blocks 1, the second block lying directly behind the one shown in this figure. Each block is provided about its periphery with a plurality of semi-cylindrical clamping recesses of different diameters for receiving the different sizes of tubes to be flared. At its upper end, each recess 15 is provided with a chamfer 16 which provides a back-up surface for the tube when the cone is forced therein during the tube flaring operations.

The neck of the yoke 12 is provided in the usual man ner with a threaded hole for receiving a threaded advancing spindle 2%). On the lower end of the spindle is mounted a flaring cone 21 of conventional design which is adapted to be forced into the end of the tube 10 held in the clamping die 11 when the spindle is rotated by means of a handle 22 secured on the upper end of the spindle. As the pointed end of the cone 21 is forced downwardly into the open end of the tube It), the sidewalls of the tube will be spread outwardly at an angle corresponding to the angle of inclination of the sides of the cone as shown in Fig. 2.

The clamping die construction shown in Fig. 2 follows the teachings of the prior art in which a die block 25, formed with a semicylindrical clamping recess 26 for receiving a tube 27 to be flared, is provided at its upper end with a chamfer 28 the inclination of which is the same as that of the flaring cone 29. Accordingly, when the end of the tube is flared outwardly by the cone 29 being forced therein, as indicated in Fig. 2, a sharp corner will be produced where the bottom of the flare joins the cylindrical portion of the tube 27. This is due to the sharp corner 30, formed by the intersection of the bottom of the chamfer with the cylindrical wall of the clamping recess 26 being forced into the wall of the tube. Likewise, if excessive pressure is applied to the flaring cone, an annular indentation will be formed in the outside wall of the flare by the sharp corner 31 formed by the intersection of the upper edge of the chamfer 28 with the top face of the clamping block. The tube will be greatly weakened at these points, particularly at the point where the bottom of the flare joins the cylindrical portion of the tube 27. The life of 35 is formed with a semicylindrical clamping recess 36 for receiving a tube 37 to be flared. At the upper end of the recess 36 is a chamfer 38 which, as clearly shown in Fig. 3, is pitched at a steeper angle than the walls of the cone 39. Consequently, when the cone is forced into the end of the tube, the point of maximum pressural contact of the outer wall of the flare against the surface of the clamping block will be at the upper end of the chamfer where it intersects with the top face of the clamping block. Also, the corner formed by the bottom of the chamfer with the cylindrical wall of the recess 36, which corner is indicated by reference numeral 4-0 in Fig. 3, will now he below the point of bend in the tube 37. Hence, the flared tube will be formed with a small fillet, or curve of small radius, as indicated by reference numeral 41, at the point where the flare joins the tube. The creation of a sharp corner at this critical location on the tube will thereby be avoided.

With a 45 cone, the angle of the chamfer 38 (Fig. 3) is preferably in the neighborhood of 35 to 40 so as to afford ample clearance between the bottom of the flare and'the lower portion of the chamfer. To avoid any possibility of the formation of an annular indentation in the outside wall of the flare at the upper end of the chamfer,

the corner formed by the intersection of the chamfer with the top face of the die may be rounded as indicated by reference numeral 42.

Another form of my invention is shown in Fig. 4 wherein the construction illustrated in Fig. l is shown on a much larger scale. As illustrated herein, the chamfer 16, like the chamfer 38 (Fig. 3), is pitched at a steeper angle than the sides of the cone 21, though to a lesser degree as hereinafter specified, so as to provide relief in the die at the bottom of the chamfer as explained earlier herein, i. e., to relieve the pressure on the tube at the bottom of the chamfer. However, to provide room for the tube 10 to bend at the point where the bottom of the flare connects with the cylindrical portion of the tube so as to provide a transition fillet portion between the cylindrical wall portion of the tube being flared and the conical wall portion of the flare, indicated by reference numeral in Fig. 4, the upper end of the recess 15 is counterbored as indicated at 46 thereby providing additional relief in the vicinity of the bottom of the chamfer. This counterbore is preferably of a cylindrical character and is of only slightly greater diameter than the clamping recess 15. The effect of the counterbore is to remove the bottom portion of the chamfer 16, the portion removed preferably being in the neighborhood of from 10 to 40%. The depth of the counterbore, that is the point at which the counterbore steps, which is indicated by reference numeral 47 in Fig. 4, is not critical but has the function of determining the radius of curvature of the fillet at the bottom of the flare. That is, the greater the depth of the counterbore, the larger the radius of the fillet since the transition fillet portion will be coextensive with the relief provided in the die. In the construction shown in Fig. 4, the angle of inclination of the chamfer 16 is preferably in the neighborhood of 40 to 43, i. e., 2 to 5 less than that of the cone, and the corner at the top of the counterbore is rounded as indicated by reference numeral 49. Also, the corner at the top of the chamfer is rounded as indicated by reference numeral 48 in the same manner and for the same purpose as described earlier herein in connection with the embodiment shown in Fig. 3.

While I have described my invention in connection with a particular form of embodiment thereof and, have used, therefore, certain specific illustrations and descriptions thereof, it is to be understood that the present disclosure is illustrative rather than restrictive and that changes and modifications may be resorted to without departing from the spirit or scope of the claims which follow.

Having thus described my invention, what I claim as new and useful, and desire to secure by United States Letters Patent, is:

1. A tube clamping device for use with a tube flaring tool having a flaring cone comprising a pair of separable dies each having one or more semicylindrical recesses formed therein, the recesses in one of said dies being complementary to the recesses in the other of said dies, a chamfer on the upper edge of each recess for supporting the outer face of the flare as it is formed on the end of the tube, and means for providing a transition fillet portion between the cylindrical wall portion of the tube being flared and the conical wall portion of the flare, said means including a relieved die wall surface extending circumferentially around the base of each chamfer and restricted to the transition fillet portion of the tube so as to prevent contact of the outer face of said transition fillet portion of the tube with the relieved die wall surface resulting from the application of a normal axial force to said flaring cone during the flaring or burnishing operation.

and the tube wall to occur at the top edge of the chamfer.

References Cited in the file of this patent UNITED STATES PATENTS Timken Dec. 30, 1919 Davies Feb. 10, 1931 Bratz Jan. 7, 1941 Wilks Aug. 7, 1951 OTHER REFERENCES Pages 157, 158 and 159 of a book entitled Press- Working of Metals by Oberlin Smith, copyrighted in 1896 by John Wiley and Sons, a copy of which may be found in Div. 14, and having library marking of TS-253-.S6.