Nov. 23, NH c. W. SCHAEFFER BENDI NU APPARATUS 2 Sheets-Sheet 1 Filed June 17, 1969 35 INVENTOR Char/es 1/14 Sc/raef/Er United States Patent 3,621,704 BENDING APPARATUS Charles W. Schaeifer, Lebanon, Pa., assignor to Bethlehem Steel Corporation Filed June 17, 1969, Ser. No. 834,003 Int. Cl. B21d 9/05, 28/00 U.S. Cl. 72-339 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This invention relates generally to an apparatus for making a product from a strip of metal and more specifically to apparatus which shears a blank from the strip and bends the blank about a mandrel.
Heretofore, products, such as the mine roof expansion shell disclosed in U.S. Pat. No. 3,000,254 to Hottenstein, were made by casting metal into a mold. The products so made are relatively expensive. While some products, such as the tubular articles disclosed in U.S. Pat. No. 2,126,473 to Keller, were made by shearing a blank from a strip of metal and bending the blank about a mandrel, the bending operation was relatively inefiicient and expensive due to the complexity of the bending dies and the number of bending steps required to arrive at the finished product.
SUMMARY OF THE INVENTION An object of this invention is to provide apparatus capable of efficiently and inexpensively making a product, such as an expansion shell.
This object can be attained by providing an apparatus which feeds a strip of metal to an arrangement of dies which successively shears a plurality of notches along one side of the strip, cuts a blank from the strip and bends the blank about a mandrel. The bending step is accomplished by a pair of pivotally mounted dies which force the blank to conform to the shape of the mandrel.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of the apparatus of this invention.
FIG. 2 is a sectional view taken along the line 22 of FIG. 1.
FIG. 3 is a sectional view taken along the line 33 of FIG. 1.
FIGS. 4, 5 and 6 are sectional views showing successive steps in the operation of the cutoff and bending station dies.
FIG. 7 is a plan View of the strip at the various stations.
FIG. 8 is a sectional view taken along the line 8-8 of FIG. 7.
FIG. 9 is a view taken along the line 99 of FIG. 7.
DETAILED DESCRIPTION OF THE DRAWINGS The apparatus of this invention is arranged as a threestation die set. With particular reference to FIG. 1, the first station is generally indicated as 10, the second station as 11, and the third station as 12. The die set is of a type well known in the art with the lower tools fixed to the bed plate of a vertical press by means of a lower mounting plate 13, and the upper tools fixed to the movable 3,621,704 Patented Nov. 23, 1971 member of the press by means of an upper mounting plate 14. Thus, the upper mounting plate 14 and the tools attached thereto are movable toward and away from the lower mounting plate 13 and its tools. A strip of metal is fed between the upper and lower tools along the line 16. The lower tools support the stri and the upper tools cooperate with the lower tools to make the desired product.
While the die set of this invention is described as mounted on a vertical press with the upper mounting plate 14 movable with respect to the lower mounting plate 13, it is obvious that the die set could be mounted on any type press and that the lower mounting plate 13 could be adapted to move relative to the upper mounting plate 14.
U.S. Pat. No. 1,632,462 to Candee discloses a power press which could be used to produce the desired movement between the upper and lower tools. To the extent that the means to produce such movement is necessary for a complete disclosure of this invention, the disclosure of the above patent to Candee is hereby incorporated by reference.
FIG. 1 shows the die set in the closed position, i.e., the upper tools have moved downwardly to their lowest position. Line 16 indicates the approximate centerline of the strip 15 as it is fed between the tools. Rollers 17 intermittently feed the strip 15 between the tools along line 16 in a manner well known in the art. In addition guides 18 aid in properly positioning the strip 15 with respect to the tools.
As shown in FIG. 8, the strip 15 of metal has a transverse cross section similar to the cross section of a leave 4 shown in FIG. 2 of the above patent to Hottenstein. However, this cross sectional shape is by way of illustration and this invention may be applied to other cross sectional shapes depending on the desired product.
FIRST STATION Referring to FIGS. 1 and 7, the first station tools shear a plurality of notches 19 along one side of the strip 15 and thus forms four leaves 20 of an expansion shell. The upper tools include four shear knives 21 which are mounted in a holder 22 which bears against liner 23 and is secured to the upper mounting plate 14. The lower tools include a lower die 24 having four openings 25 therein and secured to lower mounting plate 13. The openings 25 of die 24 are in vertical alignment with openings 68 in lower mounting plate 13. Each knife 21 is vertically aligned with an opening 25. The shape of each opening conforms to the shape of a knife 21 which is shaped to produce the keyhole shaped notch 19. A stripper plate 26 is secured to lower die 24 and acts to free the strip 15 of metal from the knives 21 after notches 19 have been made in the strip 15. Since stripper plates are well known in the art, further description of the stripper plate 26 appears unnecessary.
SECOND STATION Referring to FIGS. 1, 3, 7 and 9, the second station tools contact the leaves 20 formed in the first station and form chamfers 27 along the edges of the serrated portions 28 of the leaves 20. The upper tools include a forming die 29 mounted in die holder 30 and secured to the upper mounting plate 14. A liner 3.2 is positioned between the upper mounting plate 14 and the forming die 29 and die holder 30. The face 33 of the forming die 29 is serrated to conform to the serrated portion 28 of the strip 15, and also arcuate to produce the chamfers 27 on the leaves 20. The lower tools include a die 34 and a strip guide 25 secured to die 34 by a bolt 36 which passes through a hole in the guide 35 and is in threaded engagement with a tapped hole in the die 34. The edge of strip 15 engages the edge 37 of guide 35. Spring 38 allows the guide 35 to adjust to minor irregularities in the width of the strip 15.
Obviously, the above first and/ or second station tooling could be omitted if the product to be made does not require such tooling.
THIRD STATION The third station tools shear a blank 39, FIG. from the strip 15 and bend the blank 39 about a mandrel 40. As best shown in FIG. 1, the upper tools include die holder 41 which is positioned against a liner 42 and secured to the upper mounting plate 1 4, a pair of vertical members 43 which are secured to the ends of die holder 41, and a pair of dies 44, 44 pivotally attached to the die holder 41. Each die 44 is pivotally attached to the die holder 41 by means of a pin 45 which passes through a hole in the die 44 and a similar hole in an integral clevis portion 46 of the die holder 41.
Referring to FIGS. 1 and 2, the lower tools include stop 67, mandrel 40, mandrel support member 47 and means to eject a bent blank from the mandrel 40. The stop 67 is attached to lower mounting plate 13. The mandrel support member 47 is attached to the lower mounting plate 13, and the mandrel 40- has an integral shank portion 48 attached to the support member 47. Mandrel 40 extends above an opening 69 in lower mounting plate 13-. The means to eject a bent blank from the mandrel 40 includes four pins 49 which extend through holes in the support member 47 adjacent the outer surface of the mandrel 40. A compression spring '50 which surrounds each pin 49 urges the pin 49 and the piston 51, which is slidably mounted within a cylindrical opening 52 in support member 47, to the left as viewed in FIG. 2. Each spring 50' has one end in contact with the support member 47 and the other end in contact with the head of a pin 49. An O-ring 65 fixed to piston 51 seals the space between the piston 51 and the inner surface of the cylindrical opening 52. Attached to the end of the support member 47 opposite the mandrel 40 is a fitting 53 which includes a passageway 66 for the admission of air pressure to force the piston 51 and pins 49 to the right. In so moving, the pins 49 contact a blank which is bent about the mandrel 40 and eject the bent blank from the mandrel 40. After the air pressure has been removed springs 50 cause the piston 51 and pins 49 to return to the position shown in FIG. 2.
As shown in FIG. 4, pins 45, 45 which pivotally mount dies 44, 44 to the die holder 41, extend parallel to a plane which includes the line 54, extends perpendicular to the longitudinal centerline of the strip 15, and passes through the longitudinal axis 55 of the mandrel 40, also shown in FIG. 2. In addition, the pins 45 are displaced on opposite sides of this plane. Each die 44 includes a vertically extending leg 56 and a horizontally extending leg 57. The weight of each die 44 is distributed so that the die 44 naturally assumes the position shown in FIG. 4. The relative positions between the horizontal leg 57, vertical leg 56 and the pin 45 of each die 44 is such that an upward force on the vertical leg 56 indicated by arrows SSL and 58R, for the left and right die 44 respectively, will tend to rotate the die in the direction indicated by arrows 59L and 59R, while an upward force on the horizontal leg 57 indicated by arrows 60L and 60R, for the left and right die 44 respectively, will rotate the die in the direction indicated by arrows 61L and 61R. As to rotation in the direction indicated by arrows 59L and 59R, it Can be seen that vertical members 43 act as stops and prevent such a rotation of the dies.
As the die holder 41 moves from the position shown in FIG. 4 to that of FIG. 5, the right vertical member 43 cooperating with the edge 68 of die 34 shears a blank 39 from the strip 15. In addition, the vertical members 43 and the vertical legs 56 of the dies 44 cause the blank 39 to be bent about the upper two sides of the mandrel 40. It can also be seen that a working face of each die,
i.e. the surface of each die 44 which comes in contact with the blank 39 and indicated by numeral 62, can no longer have straight line vertical movement because a portion 63 of the horizontal leg 57 working face is in contact with a portion of the blank 39 which has been bent about the mandrel 40. Thus, as the die holder 41 moves from the position shown in FIG. 5 to the position shown in FIG. 6, the dies 44 rotate in the direction of arrows 61L and 61R for the left and right die 44, respectively, because of the reaction between the stationary mandrel 40 and the working face on the horizontal leg 57. In so rotating, the vertical leg 56 wraps the blank 39 completely about the mandrel 40- to form an expansion shell 70.
SEQUENCE OF OPERATION During the following sequence of operation, the lower mounting plate 13 and its tools remain stationary, and the upper mounting plate 14 moves between a first position (hereinafter referred to as position A), Le. the upper mounting plate 14 is raised so that the lower ends of the shear knives 21 are above the strip 15 and the tools of the third station are positioned as shown in FIG. 4, and a second position (hereinafter referred to as position B), i.e. the upper mounting plate and its tools are positioned as shown in FIG. 1.
First step. A strip 15 of metal is fed by rollers 17 to the first station 10- while the upper mounting plate 14 is in position A. The upper mounting plate 14 is then moved to position 1B and in so doing knives 21 cooperate with openings 25 in lower die 24 to shear four notches 19 along one side of strip 15. The upper mounting plate is then returned to position A.
Second step. Rollers '17 feed the strip 15 into the second station 11. The upper mounting plate is then moved to position B. During this movement, four additional notches are sheared in the strip at the first station 10 as described above. In addition, the forming die 29 and die 34 of the second station 11 cooperate to form chamfers 27 on the serrated portion 28 of the leaves 20 formed in the first station 10. The upper mounting plate 14 is then moved to position A.
Third step. Rollers 17 feed the strip 15 into the third station 12 until the end of the strip contacts stop 67. The upper mounting plate 14 is then moved to position B. During this movement, the tools of the first station 10 and second station 11 performed the shearing and forming steps described above. In addition, the right vertical member 43 cooperates with edge 68 of second station lower die 34 to shear a blank 39 including four leaves 20 from the strip 15. The vertical members 43 and vertical legs 56 of dies 44 bend blank 39 about the upper two sides of the mandrel 40'. The working face 62 of horizontal legs 57 of dies 44 come in contact with the strip 15 which is bent about the mandrel 40. The dies 44 rotate in the direction of arrows 61L and 61R and the working face of the vertical leg 56 completes the bending of the blank 39 about the lower two sides of the mandrel 40 to form an expansion shell 70. The upper mounting plate is then moved to position A. Air pressure is then supplied through passageway 66 of fitting 5-3 to cylindrical opening 52. Thereupon piston 51 moves pins 49 to the right from the position shown in FIG. 2 and the formed shell 70 is ejected from the mandrel 40. Pressure is then removed from. the piston 51, and springs 50 forces pins 49 and piston 51 to the position shown in FIG. 2. Thereafter, the above third step is repeated.
While the above description is directed to an expansion shell having four leaves and bent around a square mandrel, this invention can be used to make shells having any number of leaves and to bend blanks around a mandrel having other than a square shape. In addition, as stated above this invention can be used to make products other than expansion shells.
I claim: 1. Apparatus for bending a strip of metal comprising: (a) a mandrel in contact with one side of said strip intermediate the ends thereof,
(3) means to bend said blanks into an expansion shell comprising:
(a) a mandrel in contact with one side of said blank intermediate the ends thereof,
(b) a die holder disposed adjacent the other side of 5 (b) a die holder disposed adjacent the other said strip, side of said blank,
(c) a pair of dies pivotally mounted in said die holder (c) a pair of dies pivotally mounted in said between a pair of vertically extending members atdie holder, each of said pair of dies havtached to said die holder, each of said pair of dies ing a Working face, the pivotal axes of said having a substantially vertically extending leg arpair of dies extending parallel to and disranged to contact a vertically extending member and placed on opposite sides of a plane suba substantially horizontally extending leg the pivotal stantially perpendicular to said strip and axes of said pair of dies extending parallel to and passing through the longitudinal axis of displaced on opposite sides of a plane substantially said mandrel, perpendicular to said strip and passing through the 1 (d) means for moving the die holder tolongitudinal axis of said mandrel, ward and away from said mandrel, and
(d) means for moving the die holder toward and (e) the location of the axes and the workaway from said mandrel, and ing faces of said pair of dies being such (e) the location of the axes and said legs of said pair that on movement of the die holder toof dies being such that on movement of the die ward the mandrel said pair of dies contact holder toward the mandrel said vertically extendsaid blank to bend said blank about a ing members and said vertically extending legs of portion of said mandrel and further movesaid pair of dies contact said strip to bend said strip ment of the die holder toward the mandrel about a portion of said mandrel and upon further causes said pair of dies to rotate on their movement of the die holder toward the mandrel, axes solely by reaction between the mansaid horizontally extending legs of said pair of dies contact said strip causing said pair of dies to rotate on their axes solely by reaction between the mandrel and said horizontally extending legs of said pair of dies to further bend said strip about said mandrel.
2. Apparatus of claim 1 wherein said mandrel has a substantially square transverse cross section and a diagonal of said square lies in said plane.
3. Apparatus of claim 1 including means to eject the 5. The apparatus of claim 4 further comprising means to form a chamfer along a portion of the sheared edges of the notches.
References Cited UNITED STATES PATENTS bent strip from said mandrel. 3 2,477,910 8/ 1949 Tal 72383 4. Apparatus for making an expansion shell having a 2,437,810 1 9 Hunt 72-383 plurality of leaves comprising: 2,497,622 /1950 Mueller 72-383 (a) means for feeding a strip of metal between opposed die means, (b) said die means including 1) means to shear a plurality of notches along one side of said strip to form the leaves of said shell, (2) means to shear a blank including a plurality of leaves from said strip, and 45 CHARLES W. LANHAM, Primary Examiner R. M. ROGERS, Assistant Examiner US. Cl. X.R. 72383, 387