US3068929A - Tube pointer - Google Patents

Description

D. W. ROW'ELL TUBE POINTER Dec. 18, 1962 2 Sheets-Sheet 1 Filed April 22, 1960 FIG. 2

a m F INVENTOR. DOUGLAS W- ROWELL ATTORNEYS Dec. 18, 1962 D. w. ROWELL TUBE POINTER 2 Sheets-Sheet 2 Filed April 22, 1960 FIG. 6

INVENTOR DOUGLAS W. ROWELL.

BY fzwwug W ak Q ATTORNEYS 3,058,929 Patented Dec. 18, 1962 nice 3,068,929 TUBE POINTER Douglas W. Rowell, North Woodbury, Conn., assignor to Anaconda American Brass Company, a corporation of Connecticut Filed Apr. 22, 1960, Ser. No. 23,953 9 Claims. (Cl. 153-34) This invention relates to the pointing of tubes and, more particularly, to a new method and apparatus for pointing tubes wherein cooperating movable and stationary dies deform and compact an end portion of the tube in two strokes into a polygonal cross section substantially smaller than the across section of the tube.

Before a tube'is drawn, it is necessary to point or reduce the diameter of the end portion of the tube so that it can be inserted through the die and be grasped by tongs or other gripping device of the drawing apparatus, Though such reduction in diameter has often been accomplished by necking down the end portion of the tube in a swaging operation, it has been found to be quicker and easier to collapse the tube end portion without upsetting the wall or substantially displacing the metal as in swaging. However, presently available methods of collapsing the end portion of tubes entail considerable die wear and produce collapsed portions which are either lacking in symmetry or are too large to be repeatedly insorted through a considerable number of successively smaller dies. Asymmetry in a tube point gives rise to stress concentrations which often cause breakage of the pointed portion of the tube during'drawing. Short die life and the relatively large size of the tube points are disadvantages which increase operating costs and scrap losses.

' The major purpose of the present invention is to provide a new method and apparatus for pointing tubes by the wall-collapsing method which overcomes these various shortcomings in the means presently available, According to the invention, a pointed end portion of polygonal cross section is formed on the tube by two rapid immediately successive strokes of cooperating movable and stationary dies. (The term polygonal is used here and throughout the specification and claims in its accepted meaning of more than four sides.) The walls of the tube'are compressed solidly into this polygonal shape without causing substantial flow of metal and thus the work required to accomplish the operation is minimal. it has been found in practice that the resulting point can be made sufficiently small in size relative to the original tube diameter to permit the tube to be inserted into and drawn through a considerable series of successively smaller dies before it need be repointed. At the same time, the polygonal shapes themselves possess good symmetry, and can readily be formed symmetrically with respect to the cylindrical tube, so as to minimize the risk of concentrations of stress during the drawing operation which might cause fracture of the point. The point is formed without reducing the thickness of the tube walls, so the point remains as strong for pulling through the dies as the main body of the tube. Furthermore, the polygonal point is formed in a fashion which increases die life by substantially reducing the wear to which the forming dies are subjected.

The tube pointing apparatus of the invention comprises a frame and a stationary die afiixed to the frame. First and second movable dies are displaceable between open and closed positions relative to the stationary die. Means are included for forcibly displacing the movable dies between their open and closed positions. The dies together partially define an opening sufficiently large to receive the tube to be pointed when the movable dies are in their open position. When the movable dies are in closed position, the dies together define a cavity of polygonal cross section which is substantially less in maximum width (corner to corner) than the outside diameter of the tube. In this cavity, the stationary die defines at least two adjoining sides of the polygon and the first and second movable dies define the remaining sides thereof.

In a preferred form of the apparatus, the cavity is of hexagonal cross section. The stationary die then defines three adjoining sides of the hexagonal cavity, the first movable die defines one side, and the second movable die defines the remaining two adjoining sides.

The tube may first be deformed by one movable die and then by the other in two immediately successive strokes. Preferably, the first movable die in actuated be? fore the second movable die to partially flatten the tube. The tube is thus prepared for actuation of the second movable die whereby the partially flattened configuration is collapsed into an almost solid polygonal point. There is very little sliding contact between the tube and the dies in forming the point in this manner and hence die wear is minimized. Also, a great amount of compression of the collapsed wall is made possible so that the poly: gonal point is exceptionally compact, without reducing the thickness of the tube walls.

The invention also provides a new method which is carried out by means of the apparatus. In general, the method comprises the steps of partially flattening the portion of the tube to be pointed into substantially oblong cross sectional shape having rounded ends. The rounded ends are then compressed toward one another while the remainder of the portion is constrained from outward dis: placement. Hence, the greater part of the portion of the tube being pointed is collapsed inwardly. The compression is ceased when the end portion of the tubej'is substantially fully compacted into a polygonal cross section.

A preferred embodiment of the new apparatus illustrating the steps of the method is shown in the accompanying drawings, wherein FIG. 1 is a schematic fragmentary elevation of the apparatus partly in section showing the movable dies in open position with a tube to be pointed into hexagonal cros section received between the dies;

FIG. 2 is a similar view showing the first movable die after it has reached its closed position and the second movable die still in its open position;

FIG. 3 is a similar view showing both movable dies in their closed position and the tube pointedin hexagonal shape;

FIG. 4 is a fragmentary perspective view partly broken away showing the resulting hexagonal end portion of the tube;

FIG. 5 is a view similar to FIG. 1 showing dies for forming an octagonal point on the tube;

FIG. 6 is a view similar to FIG. 2 of the apparatus of FIG. 5;

FIG. 7 is a view similar to FIG. 3 showing the dies fully closed and the tube pointed in octagonal shape; and

FIG. 8 is a fragmentary perspective view partly broken away showing the resulting octagonal end portion of the tube.

Referring first to the embodiment of FIGS. 1-4, a stationary frame lit) is provided to define adjoining vertical 5 and horizontal die supporting surfaces 11 and 12 respecforcibly displaced toward the respective vertical and horizontal surfaces of the frame.

Affixed to the frame i a stationary die which (in the form shown) is made up of two blocks 16 and 17. One die block 16 rests on the horizontal surface 12 and abuts the vertical surface 11 of the frame, and the other die block 17 also rests on the horizontal surface 12 of the frame and adjoins the lower portion of the first die block 16. The die blocks 16 and 17 are disposed in opposition to the horizontal plunger 14 and vertical plunger 13 respectively. Each die block has a length perpendicular to the axes of both plungers which is at least equal to the length of the pointed portion to be formed on the tube.

Formed in the vertical surface of the first die block 16 which faces the horizontal plunger 14 is a concave V-shaped groove 19 extending perpendicular to both plunger axes throughout the length of the die block 16. The groove is defined by two fiat surfaces of equal dimension which converge at an included angle of substantially 120. Adjoining and extending upwardly from the top edge of the groove 19 is a vertical sliding surface on the die block 16. The upper surface 22 of the second die block 17 adjoins the lower edge of the groove 19 and is flat and horizontal. Thus, it is perpendicular to the first sliding surface 20 on the die block 16, and forms an included angle of substantially 120 with the lower of the two fiat surfaces defining the groove 19.

Aifixed to the face of the vertically movable plunger 13 is a first movable die 23. The movable die 23 is formed with a working face which is fiat and horizontal and which is therefore parallel and opposed to the surface 22 of the lower stationary die block 17. This first movable die 23 extends into contact with and slides against the first sliding surface 20 on the die block 16. In the retracted position of the plunger 13 shown in FIG. 1, the distance between the working face 25 of the first movable die 23 and the surface 22 of the die block 17 is greater than the outside diameter of the tube to be pointed.

A second movable die 27 is affixed to the face of the horizontally movable plunger 14. This die 27 includes a base portion 28 and a projecting portion 29 which extends therefrom between the first movable die 23 and the die block 17. Formed in the outer face of the projecting portion 29 of the second movable die 27 is a V-shaped groove 30 defined by two fiat surfaces of equal dimension which converge at an angle of substantially 120. The dimensions of the groove 30 are equal to those of the groove 19, which is directly opposite thereto. The vertical dimension of the projecting portion 29 is equal to the edge-to-edge dimension of the groove 30 formed in its outer face; and this projecting portion 29 is adapted to slide along the surface 22 of the die block 17. The outermost end of the projecting portion 29 extends from the shoulder of the base portion 28 a distance such that in the forward position of the plunger 14 the projecting portion 29 stops short of the nearest point on the die block 16 a distance equal to the Width of the fiat surfaces defining the grooves 19 and 30. In that forward position of the plunger 14, the shoulder of the base portion 28 abuts the sides of the first movable die 23 and the stationary die block 17, which serve as stops to limit the forward motion of the horizontally movable die 27.

Each of the movable dies 23 and 27 has a dimension perpendicular to the axes of both plungers which is equal to that of the stationary dies. In their open position shown in FIG. 1, the movable dies partly define an opening sufficiently large to receive the tube to be pointed.

In the operation of the new tube-pointing apparatus, the end portion of a tube 32 is inserted between the dies when the plungers 13 and 14 are in their open position.

The tube 32 should be small enough to fit between the 4 wardly to its closed position shown in FIG. 2. In this closed position, the working face 25 of the first movable die 23 stops at the upper edge of the groove 19 formed in the die block 16. As shown in FIG. 2, this causes the tube 32 to be flattened into oblong cross sectional shape having substantially parallel sides and rounded ends. It will be noted that the working face 25 of the first movable die 23 also abuts against the end of the projecting portion 29 of the second movable die 27 when this initial stroke is completed.

Next, the plunger 14 is moved forwardly into its closed position shown in FIG. 3. This causes the projecting portion 29 of the second movable die 27 to slide between the first movable die 23 and the lower stationary die block 17 into a position where the dies together define a cavity of regular hexagonal shape. The groove 19 in the stationary die block 16 defines two sides of this hexagonal cavity and a portion of the surface 22 of the stationary die block 17 defines a third side adjoining thereto. Opposite the die block 17, a portion of the working face 25 of the first movable die 23 defines one other side of the hexagonal cavity, and the remaining two adjoining sides are defined by the groove 30 in the projecting portion 29 of the second movable die 27.

While moving into its closed position shown in FIG. 3, the second movable die 27 first compresses the rounded ends of the tube 32 toward one another between the wedge-shaped grooves 19 and 30. At the same time, the parallel sides of the tube 32 are constrained between the first movable die 23 and the die block 17. This causes the parallel sides of the oblong cross section to collapse inwardly as shown in FIG. 4, and the previously rounded ends thereof are formed into a triangular shape conforming to the shape of the grooves 19 and 30. Compression of the tube in this manner ceases when the shoulder of the base portion 28 of the second movable die member 27 abuts the first movable die member 23 and the lower die block 17; and at that point the cavity formed by the dies is of the desired regular hexagonal shape.

The collapsed portion of the tube between the dies is formed into the shape shown in FIG. 4 with a definite hexagonal cross section. Two opposite sides 35 and 36 of this cross section are marked by folds where the walls of the tube were collapsed inwardly, but the remaining four sides are substantially fiat. It will be noted that the collapsed walls of the tube 32 are substantially unchanged in thickness, but are compressed together to such a degree that the point is almost solid. The maximum width of the hexagonal cross section of the pointed portion 33 (measured from corner to corner) is considerably less than the original outside diameter of the tube 32. The length of the pointed portion 33 can be varied, of course, as desired, by correspondingly varying the length (in the direction perpendicular to the plane of the drawing) of the dies in the apparatus.

Turning now to the embodiment of the new apparatus shown in FIGS. 5-8, a frame 35 is associated with vertical and horizontal plungers 36 and 37 as in the embodiment described above. Mounted on the frame 35 is a stationary die made up of two blocks 39 and 40 which are supported in the same manner as the die blocks 16 and 17. The first die block 39 has a concave V-shaped groove 41 formed in its vertical surface opposite the horizontal plunger 37. This groove defines an included angle of The second block 40 also includes a 135 V- shaped groove 42 opposite the vertical plunger 36 and the immediately adjoining surfaces of these two grooves also define an included angle of 135.

First and second movable dies 44 and 45 are mounted on the vertical and horizontal plungers 36 and 37 respectively to slide against the die blocks 39 and 40 as in the previous embodiment. However, a V-shaped groove 46 is formed in the first movable die 44 and defines an included angle of 135. Similarly, the second movable die 45 defines a 135 V-shaped groove 48. Hence, when the dies 44 and 45 are brought together they define a regular octagonal cavity with the stationary die blocks 39 and 48.

The end portion of a tube 50 which is to be pointed is first inserted between the stationary and movable dies as shown in FIG. 5. The vertical plunger 36 is then actuated to bring the first movable die 44 down onto the end of the tube 50 to liatten it into the substantially elongated shape shown in FIG. 6. The ends of this oblong cross section arerounded. Next, the horizontal plunger 3'7 is actuated to bring the second movable die 45 against the flattened end portion of the tube so that the tube is collapsed as shown in FIG. 7. Upon retraction of the dies, the tube is withdrawn and formed with a pointed portion 52 as shown in FIG. 8. The portion 52 is of substantially regular octagonal shape with the greater part of the tube walls collapsed inwardly in a substantially solid fashion.

It is evident that the regular polygonal portions of the tubes pointed by these embodiments of the new apparatus are of symmetrical shape and thus are not susceptible to extreme stress concentrations when grasped by tongs during drawing. Also, the polygonal pointed portions are of small size compared to the original tube and thus can be received in a wide size range of grips. Such fiat-sided configurations on the tube points need not be specially matched to the gripping jaws as is the case with conventional round points. By collapsing a tube into the polygonal shapes shown, very little wear is exerted on the dies of the apparatus because there is a minimum of sliding contact between the walls of the tubes and the dies. Furthermore, there is virtually no reduction in thickness of the metal in deforming the walls of the tubes in the manner described, so that the new pointing operation can be performed quickly with a minimum of work and without reducing the tensile strength of the tube at its point in comparison with the cylindrical body of the tube.

I claim:

1. Tube pointing apparatus comprising a frame, a stationary die affixed to said frame, first and second movable dies displaceable at right angles to one another between open and closed positions relative to said stationary die, means for forcibly displacing said movable dies between their open and closed positions, said dies together partially defining an opening sufiiciently large to receive the tube to be pointed when said movable dies are in open position, said dies together defining a cavity of polygonal cross section substantially less in maximum width than the maximum width of said tube when said movable dies are in closed position, said first and second movable dies defining at least three adjoining sides of said cavity.

2. Tube pointing apparatus according to claim 1 wherein said cavity is of hexagonal cross section, said stationary die defining three adjoining sides of said cavity, said first movable die defining one side of said cavity, and said second movable die defining two adjoining sides of said cavity.

3. Tube pointing apparatus according to claim 1 wherein said cavity is of octagonal cross section, said stationary die defining four adjoining sides of said cavity, said first movable die defining two adjoining sides of said cavity, and said second movable die defining two adjoining sides of said cavity.

4. Tube pointing apparatus comprising a frame, a stationary die affixed to said frame, first and second movable dies displaceable at right angles to one another between open and closed positions relative to said stationary die, said stationary die defining a first surface against which said first movable die is adapted to slide between its open and closed positions, said stationary and first movable dies defining parallel second surfaces perpendicular to said first surface against which said second movable die is adapted to slide from its open to its closed position, means for forcibly displacing said movable dies between their open and closed positions, said dies together partially defining an opening suificiently large to receive the tube to be pointed when said movable dies are in open position, said dies together defining a cavity of regular polygonal cross section substantially less in maximum width than the maximum width of said tube when said movable dies are in their closed position, said stationary die defining at least two adjoining sides of said cavity, said first movable die defining at least one side of said cavity, and said second movable die defining at least two adjoining sides of said polygonal cavity.

5. Tube pointing apparatus comprising a frame, a stationary die afi'ixed to said frame, first and second movable dies displaceable at right angles to one another between open and closed positions relative to said stationary die, said stationary die defining a first surface against which said first movable die is adapted to slide between its open and closed positions, said stationary and first movable dies defining parallel second surfaces perpendicular to said first surface against which said second movable die is adapted to slide from its open to its closed position, means for forcibly displacing said movable dies between their open and closed positions, said dies together partially defining an opening sufliciently large to receive the tube to be pointed when said movable dies are in open position, said dies together defining a cavity of regular hexagonal cross section substantially less in maximum width than the maximum width of said tube when said movable dies are in their closed position, said stationary die defining three adjoining sides of said cavity, said first movable die defining one side of said cavity, and said second movable die defining two adjoining sides of said hexagonal cavity.

6. Tube pointing apparatus according to claim 5 wherein said parallel second surfaces on said stationary and first movable dies respectively are coplanar with and adjoin diametrically opposite parallel sides of the regular hexagonal cavity defined by said dies when the movable dies are in closed position.

7. Tube pointing apparatus comprising a frame, a stationary die affixed to said frame, first and second movable dies displaceable at right angles to one another between open and closed positions relative to said stationary die, said stationary die defining a first surface against which said first movable die is adapted to slide between its open and closed positions, said stationary and first movable dies defining parallel second surfaces perpendicular to said first surface against which said second movable die is adapted to slide from its open to its closed position, means for forcibly displacing said movable dies between their open and closed positions, said dies together partially defining an opening sufficiently large to receive the tube to be pointed when said movable dies are in open position, said dies together defining a cavity of regular octagonal cross section substantially less in maximum width than the maximum width of said tube when said movable dies are in their closed position, said stationary die defining four adjoining sides of said cavity, said first movable die defining two adjoining sides of said cavity, and said second movable die defining two adjoining sides of said octagonal cavity.

8. A method of pointing tubes which comprises initially partially flattening the portion of the tube to be pointed with a single flattening stroke into substantially oblong cross sectional shape having rounded ends, compressing at least part of said rounded ends toward one another with a single compression stroke along a single side section of the tube while constraining the remainder of said portion of the tube from outward displacement, thereby collapsing inwardly the greater part of said portion of the tube, and ceasing said compression when said portion of the tube is substantially fully compacted into a polygonal cross section.

I 9. A method of pointing tubes which comprises initially partially flattening the portion of the tube to be pointed with a single flattening stroke into oblong cross sectional shape having substantially parallel sides and rounded ends,

7 compressing said rounded ends toward one another between concavely wedge-shaped dies with a single compression stroke along a single side section of the tube while constraining said parallel sides from outward displacement thereby forming each of the rounded ends of said 5 oblong cross section into triangular shape and collapsing inwardly a portion of the parallel sides of said oblong cross section, and ceasing said compression when said portion of the tube is substantially fully compacted into a regular hexagonal cross section.

References Cited in the file of this patent UNITED STATES PATENTS Wikstrom Jan. 16,

Oliver et a1. June 16,

Frank et a1. Jan. 3,

Rotheroe Mar. 11,

FOREIGN PATENTS Germany May 21,

Great Britain Mar. 11,

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