US3025904A

US3025904A - Machine for stretch forming mandrel supported tube-like elongated stock

Info

Publication number: US3025904A
Application number: US12161A
Authority: US
Inventors: Marco Robert F De
Original assignee: Cyril Bath Co
Current assignee: Cyril Bath Co
Priority date: 1960-03-01
Filing date: 1960-03-01
Publication date: 1962-03-20
Anticipated expiration: 1979-03-20

Description

. 3,025,904 MACHINE FOR STRETCH FORMING MANDREL SUPPORTED R. F'; DE MARCO March 20, 1962' TUBE-LIKE ELONGATED STOCK 4.Sheets-Sheet 1 Filed March 1, 1960 INVENTOR.

Poss/er f. DEM/4260 March 20,1962

R. -F. DE MARCO MACHINE FOR STRETCH FORMING MANDREL. SUPPORTED TUBE-LIKE ELONGATED STOCK Y 4 Sheets-Sheet 2 Filed March 1, 1960 INVENTOR.

205527 F 06 Mmeao In I ATTO/PNfV.

DE MARCO, I

. R. F. 3,025,904 MACHINE FOR STRETCH FORMING MANDREL SUPPORTED March 20, 1962 TUBE-LIKE ELONGATED STOCK 4 Sheets-Sheet 3 Filed March 1, 1960 INVENTOR.

05597 A '05 Mxwco ATTbR/VEK March 20,1962 R.- F. DE MA'RCO- 3,025,904 I MACHINE FOR STRETCH FORMING MANDREL SUPPORTED I TUBE-LIKE ELONGATED STOCK Filed March l, 1960 4 Sheets-Sheet 4 5" EQI INVENTOR. Passer f fifM/wco BY Y . 2 ATTORNEY;

atent @hiee Patented Mar. 20, 19:32

3,025,904 MACHINE FOR STRETCH FGRMING MANDREL SUPPORTED TUBE-LIKE ELONGATEE STQCK Robert F. De Marco, Mentor, Qhio, assignor to The Cyril Bath Company, Solon, ()hio, a corporation of Ohio Filed Mar. 1, 196%, Ser. No. 12,161 7 Claims. (Cl. 153-32) This invention relates to stretch forming machines and particularly to a stretch forming machine for forming elongated tube-like metal stock while the stock is internally supported by a mandrel to prevent its buckling and collapsing.

More specifically, the invention relates to a stretch forming machine having a gripping head arranged to grip one end of a length of tubular stock for applying endwise tension thereto for stretch forming, the head being combined with a mandrel arranged to be slid free end foremost into the stock through the end of the stock and through the gripping head, and having a portion spaced from the free end and arranged to occupy the portion of the stock gripped by the gripping head for resisting the collapse of the gripped portion of the stock, thereby assuring effective gripping of the gripped portion of the stock by the head.

Another specific object is to provide, in such a mandrel and stretch head combination, means for advancing the mandrel into the stock through the end of the stock after the end portion of the stock is disposed in position for gripping by the head but before the gripping operation, to grip the end portion of the stock with the man drel therein after the mandrel is fully inserted in the stock and maintain the grip thereon during the forming operation, and then to release the stock and withdraw the mandrel from the stock through the gripping head and end of the stock.

Another specific object is to provide means in such a machine for forming serpentine bends in the lengths of stock.

Various other objects and advantages will become apparent from the following description wherein reference is made to the drawings, in which:

FIG. 1 is a top plan view of a machine embodying the principles of the present invention, part thereof being shown in section as indicated by the line 1-1 of FIG. 2;

FIG. 2 is a front elevation, partly in section, of the machine illustrated in FIG. 1;

FIG. 3 is a vertical sectional view taken on the line 3-3 of FIG. 1;

FIG. 4 is an enlarged fragmentary top plan View of the right end gripping head and mandrel support, showing the cooperation therebetween;

FIG. 5 is a left end elevation of the gripping head and mandrel support illustrated in FIG. 4;

FIG. 6 is an elevational view taken on a line indicated at 6-6 in PEG. 5;

FIG. 7 is a top plan view illustrating a tube-like article formed from tube-like stock on the machine;

FIG. 8 is a cross sectional view of the article taken on the line 88 of FIG. 7; and

FIG. 9 is a diagrammatic illustration of a form of fiuid pressure circuit suitable for operation of the machine.

Referring first to FIGS. 1 through 3, the machine illustrated is one for forming so-called tubular stock, such as true tubes which are peripherally continuous in cross section; open sided stock such as bead trim and bumpers for automobiles; and other types of concavoconvex stock which must be reinforced by a mandrel during stretch forming. The machine comprises a supporting frame 1 arranged preferably horizontally for convenience in operation of the machine. Carried by the frame 1 is an upright column 2 on which are mounted swinging arms 3 and 3a, respectively. The arm 3 is provided with suitable bearing portions 4 at its inner end which engage the post 2 and support the arm 3 for swinging about the upright axis of the post. The arm 3a is provided with like hearing portions 4a. Since these arms 3 and 3a, and their operating parts and mechanisrns carried thereby are the same in form and function in most respects, only the arm 3 and its associated parts and mechanisms are described in detail, except as to parts or mechanisms which differ from those of the arm 3.

At its outer end, the arm 3 is provided with suitable rollers 5 which engage a track 6 carried on a support 7 which, in turn, is carried on the frame 1. The support 7 also carries an overhanging guide 8 disposed above the rollers with slight operating clearance while the rollers are in engagement with the track 6 so that the guide 8 and track 6 can constrain the arm 3 from rocking transversely of the axis of the post 2 in a vertical plane.

The positions of the arms for starting the forming operation on a length of stock are somewhat forward of the position shown in FIG. 1. For swinging the arms from their starting position rearwardly the requisite distance to form the stock, the arms 3 and 3a are provided with links it), respectively. Each link 10 is pivotally connected by a pivot 11 to its associated arm and is pivotally connected by a pivot 12. to a common driving carriage 13. The carriage 13 is mounted for sliding movement along a trackway 14 forwardly and rearwardly of the frame 1 and, in so doing, swings the arms forwardly and then from their forward positions to their rearmost positions.

In order to drive the carriage, suitable power means are provided. The power means, in the form illustrated, comprises a reversible hydraulic piston and cylinder assemblage 15 including a cylinder 16 mounted on horizontal trunnions 17 on the carriage 13. The assemblage also includes a piston 18 having a piston rod 19 which is connected at its rear end by a pivot 20 to a suitable anchor bracket 21 on the frame. Thus, upon operating the piston and cylinder assemblage 15 to extended position, the arms 3 and 3a are swung to their forwardmost positions, respectively, and upon operating the assemblage 15 to retracted position, the arms 3 and 3a are swung to their rearmost positions, respectively.

Supported on the frame 1 is a platform 25 which, in

turn, supports a side face die 26. The contour of the side face of the die is, of course, determined by the shape to be imparted to the length of stock to be stretch formed. Combined stretch forming and mandrel operating mechanisms are mounted on the arms 3 and 3a, respectively.

Referring first to the mechanism for the arm 3, this assemblage comprises a carriage 30 mounted on the arm for reciprocation therealong and driven by a reversible hydraulic piston and cylinder assemblage 31. The assemblage 31 includes a cylinder 32 in which is reciprocable a piston 33 having a piston rod 34. The head end of the cylinder 32 is pivotally connected by a pivot 35 to a rigid portion of the arm 3. The piston rod 34 is connected to a bracket 36 which is rigid with the carriage 30.

Mounted on the carriage 30 for swinging about an upright axis is a horizontally extending supporting platform 37. In order to mount the platform for such swinging, it it provided with dependent trunnion 38 which is rotatably mounted in a suitable bearing 39 carried on the carriage 34 A suitable weight supporting skid pad 44) is provided on the carriage 30 and engages a complementary pad 41 on the underside of the platform 37 for relieving the platform of overhanging stresses and loads. A suitable hold-down bracket 42 is provided on the platform 37 and is arranged to engage the underside of the margin of the skid pad 4% for preventing deflection of the platform 37 vertically.

Mounted on the platform 37 is an upright supporting post 45 which, at its upper end, carries a gripping head 46 for gripping the one end of the length of stock. Also mounted on the platform 37 is a mandrel slide .8 arranged for sliding movement in suitable guideways 49 mounted in fixed position on the supporting platform 37 so as to be reeiprocable endwise of the platform 37. Suitable guide rods 50 are connected to brackets 51 and 52 on the platform 37 and engage a suitable slide bearing, as indicated at 53, in the mandrel slide for guiding the mandrel for sliding horizontally along a lineal path endwise of the platform 37 along its guideway 49.

In order to reciprocate the mandrel slide along said path, a suitable reversible hydraulic piston and cylinder assemblage 55 is provided. This assemblage includes a cylinder 56 with a piston 57 reciprocable therein and provided with a piston rod 58. The rod 58 is connected to a forward dependent end portion 59 of the mandrel slide 48. Since the assemblage is reversible, the slide can be projected forwardly or retracted, selectively. At its outermost end, the slide 48 is provided with a mandrel head 60 carried on a suitable upright supporting pedestal 61. The mandrel head 60 is secured to one end of a mandrel 62. The mandrel may be in the form of .a plurality of nylon discs 63 of the required outline to fit the internal cross section of the stock to be formed, and held together in face to face alignment by a suitable Wire 64 so that the mandrel can bend and warp and curve and adjust itself to various bends which may be formed in the stock during the forming operation. The head 60 of the mandrel is firm and rigid and is so arranged that with the mandrel inserted in the stock the portion of the stock gripped by the gripping head 46 contains the mandrel head and is thereby prevented from collapse by the gripping head 46, thereby assuring an effective grip on the stock.

The mandrel is carried in a suitable guide 66 which has a passage therethrough to fit the mandrel and support it for endwise sliding movement.

When the mandrel head 69 is in the fully retracted position, the entry or free end 67 of the mandrel is within the stretch forming gripping head ready to be inserted into the stock through the end of the stock when the stock is inserted into the gripping head 46. This structure is best illustrated in FIGS. 4 through 6. As mentioned heretofore, the gripping head 46 is mounted on the support 45 and includes a stationary gripper jaw 70 and a movable gripper jaw 71 supported in a suitable supporting plate 72. The jaw 71 and plate 72 have cooperating slide surfaces 73 which are biased the direction of pull to be applied on the stock so that as the jaw 71 moves toward the gripping position, or to the left in FIG. 4, it moves inwardly into gripping relation to the stock. The movement necessary for engaging the stock is usually quite limited depending upon the thickness of the stock. The gripping faces of the jaws 70 and 71 are shaped to conform to the stock, as indicated at 74 and 75, respectively, and to engage a substantial area of the stock S of which a cross section is illustrated in FIGS. and 8. In order to move the jaw 71 to and from gripping positions, a reversible piston and cylinder assemblage 76 having a piston 77 and a piston rod 78 is fixedly mounted on the supporting plate 72. The rod 78 is connected to the jaw 71.

In operation, the jaws 70 and 71 are separated, the end portion of the tubular stock is moved endwise to a position therebetween, and then the piston and cylinder P assemblage 55 is operated to advance the mandrel free end foremost into the stock until the rigid head 60 of the mandrel is within the stock at a location endwise of the stock between the jaws 70 and 71. At this time, the jaw 71 is advanced, and the jaws clamp the end portion of the stock tightly against the mandrel and exerts sufficient gripping pressure for the stretch forming of the stock, the mandrel head 68 preventing deformation of the stock at the gripped portion.

In the particular form illustrated, the portion of the die 26 is relatively straight and, therefore, a very short mandrel may be used on the right-hand arm 3 as it need only be inserted into the stock slightly beyond the bend, as indicated by the radius line Y in FIG. 1. The lefthand arm 3a is provided with a structure which is similar in all respects to that heretofore described, the only difference being that the platform 84), the mandrel slide 81, the mandrel guide 82, the mandrel 83, are longer than their counterparts, the support 37, slide 48, guide 66, and mandrel 62 on the arm 3. This is because at the peak point of the die, as indicated at Z in FIG. 1, there is a bend and the stock has to be supported at this particular location. Accordingly, the mandrel 83 is made longer so that when fully inserted into the stock, its free end reaches just to or very slightly beyond the point Z in a direction toward the mandrel 63.

Thus, in FIG. 1, the left-hand portion of the stock being formed is mandrel supported interiorly from just to the right of the point Z entirely to the left-hand end of the face of the die 26. The mandrel 83 has a head 84 corresponding to the head 60 of the mandrel 62. As can be seen from FIGS. 7 and 8, the stock to be formed is first bent convexly forwardly of the machine and then near its end is reversely bent so that it is a compound or sinuous curve. For this reverse bending, there are mounted on the die 26, at opposite ends of the side face, respectively, and in spaced relation thereabove, supporting plates 85. These plates are supported by suitable bolts and sleeves 86. Reverse dies 87 are arranged to be disposed in the plane of the die 26. The dies 87 are supported on suitable guide rods 88 which protrude from the bottoms of the dies 87 a short distance, as indicated at 89. The platform 25 is provided with suitable bores 90 adjacent the opposite ends of the die 26 which receive the lower ends 89 of the rods 38 when the dies 87 rest on the upper surface of the platform 25, and thus with their faces disposed alongside the side face of the die 26. Suitable reversible hydraulic piston and cylinder assemblages 91, each including a piston 92 having a piston rod 93, are mounted on the plates with their rods 93 connected to the dies 87, respectively. These assemblages are operable to lift and lower the reverse dies 87, respectively, and to press the dies 87 firmly downwardly against the platform 25 when desired whereon they are held fixedly in position transversely of the platform by the lower ends 89 of the guide rods 88 engaging the bores in the platform 25.

In the operation of the machine, the arms are swung sufficiently forwardly, by their piston and cylinder assemblages 31, so that the gripping

heads

46 and 94 are aligned with each other in a straight line forwardly of the peak Z of the die 26. In this position, a length of tubular stock is inserted endwise into the gripping

heads

46 and 94. While so disposed, the slides 48 and 81 are moved to extended position by their associated assemblages 55 so that the

mandrels

62 and 83 enter the ends of the stock and are advanced endwise into the interior of the stock, the free or leading end of the mandrel 62 passing just beyond the radius line Y, and the free end of the mandrel 83 passing just beyond the peak Z. When the mandrels are in this position, the heads 60 and 84 are disposed endwise in the end portions of the stock which are located between the jaws of the associated gripping heads 60 and Y84, respectively. Thereupon the jaws of the gripping

heads

46 and 94 are operated by their assemblages 76 to clamp the stock firmly against the rigid heads 69 and 84 of the mandrels, the head of each mandrel acting to transmit the force applied by each of its associated jaws to its associated opposed jaw. With the parts in this condition, the piston and cylinder assemblages 15 are operated to cause the arms to swing rearwardly, thus laying the stock along the side face of the die 26 from the peak Z toward radius lines, such as indicated at the radius line Y, at opposite ends, and preferably entirely to the end of the side face of the die 26. When the stock is held in this position, the piston and cylinder assemblages 91 are operated to lower the reverse dies 87. When the dies 87 are lowered and seated, the piston and cylinder assemblages are operated to swing the arms 3 and 3a forwardly, thus imparting the reverse bend in the stock by bending it forwardly around the dies 87. This reverse bending operation is described broadly in US. Letters Patent No. 2,444,719, issued July 6, 1948, to Cyril J. Bath.

After the stock has been thus reversely bent, the stretch jaws of the head 46 are released and the mandrel 62 is withdrawn by operation of its associated slide 48 by its assemblage 55. Next, the jaws of the head 94 are released and the mandrel 83 is withdrawn by its slide 81. After withdrawal of the mandrels, then the stretch heads are retracted by the retraction of the

platforms

37 and 80 by the assemblages 15, whereupon the stock is released for removal from the machine.

Generally, suitable cut-off mechanisms may be provided in the proper position on the supporting plates 85 for cutting off the stock after it has been released by the stretch forming heads and mandrels, if desired.

A conventional knock-out mechanism may be provided for moving the piece forwardly out of position on the die 26.

For purposes of illustration, the invention 'has been described as operated hydraulically, but pneumatic fluid pressure may be used in lieu thereof.

Referring specifically to the hydraulic circuit illustrated in FIG. 9, the pressure fluid is supplied by a suitable pump 97 driven by a motor 98. The pump 97 has a pressure line 99 which is connected to a suitable valve 100 by which it is connectable to opposite ends of the piston and cylinder assemblage 15, selectively. The valve 100, as illustrated, is a three-way valve and in one position admits pressure fluid to the head end of the cylinder and vents the rod end of the cylinder to a sump. In another position, it reverses this connection. In an intermediate position, it connects both ends of the cylinder to a sump and blocks the pressure fluid from the pump, thus permitting the retraction and extension of the assemblage 15 by hand. The valve 100 may be remotely controlled by suitable solenoids 101 from a central control panel, if desired.

Similar valves are arranged for the other piston and cylinder assemblages and are operable in like manner. For example, valves 102 are provided for the cylinders 76 which operate the clamping jaws. Valves 103 are provided for the cylinder assemblages 55 which operate the

mandrels

62 and 83, and valves 104 are provided for operating the asemblages 31 for the

platforms

37 and 80. These valves are conventional valves and operate in the well known manner.

It has been found that, with this type of operation, lengths of tubular stock, such, for example, as the stock S illustrated in FIGS. 7 and 8, can be stretch formed readily. Likewise, if desired, peripherally closed tubular stock may be formed. In all such types of tubular stock, requiring the support of a mandrel during forming, the present machine can be employed, an important feature being that the mandrel is properly insertable through the stretch forming head and has a rigid head which, when the stock is gripped under pressure by the jaws of the stretch heads, prevents collapse of the stock at the gripped portion and assures (good gripping pressure for stretch forming.

The operation of the machine may be rendered automatic, semi-automatic, or manual, as desired, by the usual control cams and the like. For brevity, the machine is described and claimed herein as positioned with the swinging axis of the arms upright, using such words G as upright, horizontal, vertical, and the like. Those words are used merely to describe relative positions of various parts, not their absolute positions.

Having thus described my invention, I claim:

1. In a stretch forming apparatus, a die support, a side face die mounted thereon, gripping means to hold a length of stock, with one portion, which is spaced from one end of the stock, in fixed position relative to the die, a power operated stretch forming assembly including a stretch head operable to grip said one end of the stock and apply endwise tension to the stock, means to cause relative swinging movement of the head and die in a direction transversely of the die for laying the stock progressively on the side face of the die in a direction toward said head while the stock is held under tension by the head, opposed separable clamping jaws in the head operable by movement relative to each other to grip and release the stock, respectively, said head having a passage extending between the jaws with an open inner end and an open outer end, the inner end being at the side of the jaws toward the die and the outer end being at the opposite side of the jaws, means to operate the jaws, an elongated mandrel, mandrel supporting means supporting the mandrel for endwise movement of the mandrel relative to the stretch head from a retracted position, in which at least part of the mandrel is disposed outwardly, endwise of said passage, from the outer end of the passage, in a direction toward the inner end of the passage to an extended position in which one portion of the mandrel lies in the passage between the jaws and another portion projects beyond the inner end of the passage so as to lie within the stock selectively, and said one portion between the jaws lies in engagement with the stock when the mandrel is in the extended position and supports the stock against collapse by the force applied by the jaws.

2. The apparatus according to claim 1 wherein said one portion of the mandrel is a rigid head.

3. The apparatus according to claim 2 wherein the mandrel is flexible for the major portion of its length beyond said rigid head.

4. The apparatus according to claim 1 wherein power means are connected to the mandrel supporting means and are operable to move the mandrel to extended and retracted positions, selectively.

5. The apparatus according to claim 4 wherein said one portion of the mandrel is a rigid head, the supporting means including a slide and a member connecting the rigid head to the slide in spaced relation to the slide, said apparatus including an elongated hollow mandrel guide, said guide having a passage at one side extending along at least the major portion of its length, said mandrel and rigid head being within the guide, and said member extending through said passage and being movable therealong upon movement of the slide lengthwise of the guide.

6. In a stretch forming machine, a frame, a horizontal die support mounted thereon, a side face die mounted on the support, means to hold a length of stock with one portion, which is spaced from one end of the stock, in fixed position relative to the die, an arm, means supporting the arm for swinging about a fixed upright axis, a platform mounted on the arm for swinging relative to the arm about an upright axis, power operated stretch forming means connected to the platform and including a stock gripping head having stock gripping jaws for gripping said one end of the length of stock, a horizontal slide on the platform, a mandrel head on the slide, a mandrel connected at one end to the mandrel head and positioned to be moved thereby endwise between and beyond the jaws in a direction toward the other end of the stock so as to lie alongside at least one wall portion of the stock with the mandrel head between the jaws and lying alongside at least said wall portion of the stock, means to operate the jaws to clamp the stock when the mandrel head is between the jaws, and power means to 7 swing the arm in opposite directions about its axis, selec tively.

7. In a stretch forming machine, a frame, a horizontal die support mounted thereon, a die on the support, a pair of arms pivotally mounted on the frame for swinging horizontally toward each other, said die having an intermediate bend spaced from its ends, stretch forming assemblages on the arms, respectively, each assemblage in cluding a stretch head having stock gripping separable jaws and means for operating the jaws, said heads being arranged to grip opposite ends of a length of stock for transmitting tension thereto from the assemblages for tensioning the stock endwise, mandrel supports mounted on the arms, respectively, for movement toward and away from the heads, mandrels on the supports, respectively, and movable thereby relative to the heads endwise References Cited in the file of this patent UNITED STATES PATENTS 2,357,027 Seifried Aug. 29, 1944 2,729,265 Jones Jan. 3,1956 2,889,864 Bowser June 19, 1959 nay-a.