Apparatus for bending tubular workpieces

Abstract

A method and apparatus for bending tubular workpieces whereby a tube length is placed in front of a template and selectively driven deforming shoes urge the tube into engagement with the same. Where the desired tubular radii of curvature are relatively large the deforming shoes are driven from a stationary mount. Where shorter tubular radii are desired, generally near the tube ends, the deforming shoes are arranged such that they are incrementally translated along a path commensurable with the contour of the template. At each successive increment the deforming shoes perform a bending operation upon the tube such that it may be successively formed into its desired shape.

Description

Claims

1. An apparatus for bending a tubular workpiece to assume a shape including two substantially parallel end portions joined by a central portion of predetermined curvature, said apparatus comprising:

base plate means having a substantially horizontal upper surface,

template means including contour adjustment means mounted on said base plate surface and having a contour commensurate with said shape, said template means comprising a tape-like elastically deformable shaped member and adjustment elements rigidly supported by said base plate by means of socket members, and said template contour being adjustable within limits determined by quality variations of said workpiece,

generally horizontally displaceable shoe means adapted to deflect a straight tube length placed in front of said template means into engagement with the latter, adjacent shoe means being connected by an elastic tape extended substantially parallel to said tube length,

hydraulic cylinder means respectively drivingly connected to said shoe means,

control means selectively connecting said hydraulic cylinder means to a source of hydraulic pressurized fluid,

said displaceable shoe means comprising a first set of shoes driven by hydraulic cylinders stationarily mounted on said base plate means and adapted to bend said tube length to assume said central portion shape, and at least one second set of movable shoes, consisting of two shoes adapted to provide bending of said tube end portions,

each shoe of said second set being mounted, together with its hydraulic cylinder means, on a lever means pivotable in a plane parallel to said upper horizontal surface for shoe and cylinder movement along an adjacent tube end portion,

said control means being enabled and disabled in sequence such that

first, said first set of shoes are operated by associated hydraulic cylinders to clamp said tube to said template means at its said central portion of the tube length,

thereafter, while maintaining engagement of said shoes of said first set with said tube so that the latter is firmly clamped to said template means, said lever means is pivoted incrementally about predetermined angles and in each position so achieved, the hydraulic cylinder means of the shoes of said second set are actuated so as to incrementally bend said end portions of said tube length progressively from inner to outer ends of said end portions.

2. An apparatus as set forth in claim 1 wherein a plurality of hydraulic cylinder means are sequentially supplied with pressurized fluid from said source.

3. An apparatus for bending a tubular workpiece to assume a shape including two substantially parallel end portions joined by a central portion of predetermined curvature, said apparatus comprising:

base plate means having a substantially horizontal upper surface,

template means mounted on said base plate surface and having a contour commensurate with said shape, said template contour being adjustable within limits determined by quality variations of said workpiece,

generally horizontally displaceable shoe means adapted to deflect a straight tube length placed in front of said template means into engagement with the latter,

hydraulic cylinder means drivingly connected to said shoe means,

said displaceable shoe means comprising a first set of shoes driven by hydraulic cylinders stationarily mounted on said base plate means and adapted to bend said tube length to assume said central portion shape, and at least one second set of movable shoes, consisting of two shoes adapted to provide bending of said tube end portions,

each shoe of said second set being mounted, together, with its hydraulic cylinder means, on a lever means drivingly connected to its associated hydraulic cylinder means and pivotable in a plane parallel to said upper horizontal surface for shoe and cylinder movement along an adjacent tube end portion, and

hold-down means restraining said length of tube against vertical motion with respect to said base plate upper surface during operating periods of said hydraulic cylinder means

control means selectively connecting said hydraulic cylinder means to a source of hydraulic pressurized fluid, said control means comprising solenoid valving means associated with each of said hydraulic cylinder means and functioning to permit the flow of pressurized hydraulic fluid to the same;

pressure sensor means assoicated with each of said hydraulic cylinder means drivingly connected to said shoe means and with each of said hold-down means, and functioning to provide an output signal dependent upon the pressure exerted by said associated hydrualic cylinder means and said hold-down means;

displacement sensor means associated with each of said cylinder means drivingly connected to said lever means, and functioning to provide an output signal dependent upon the angular displacement of each of said lever means;

electric circuit means functioning to place said solenoid valving means, said pressure sensing means, and said displacement sensor means in electrical communication,

said control means being enabled and disabled in sequence to feed pressurized fluid alternatingly to said hydraulic cylinder means and to said hold down means such that first, said first set of shoes are operated by associated hydraulic cylinders to clamp said tube to said template means at its said central portion of the tube length,

thereafter, while maintaining engagement of said shoes of said first set with said tube so that the latter is firmly clamped to said template means, said levers are pivoted incrementally about predetermined angles and in each position so achieved, the hydraulic cylinder means of the shoes of said second set are actuated so as to incrementally bend said end portions of said tube length progressively from inner to outer ends of said end portions.

4. An apparatus as set forth in claim 3 wherein at least one of said hold-down means is hydraulically operable.

5. An apparatus as in claim 3 wherein said electric circuit means comprises at least one switching means assoicated with each of said solenoid valving means, said pressure sensor means, and said displacement sensor means, and functioning to selectively permit electric current flow to each of the same.

6. An apparatus as in claim 3 wherein said control means comprises:

a first and second of said switching means disposed in series functioning to permit electric current flow to a first solenoid valving means associated with a first hydraulic cylinder means mounted substantially along the line of symmetry of said apparatus, said first solenoid valving means operates to permit the flow of pressurized hydraulic fluid to said first hydraulic cylinder means, causing the same to drive said tube into pressurized engagement with said template means, a first pressure sensor means associated with said first hydraulic cylinder means provides an electric output signal to a third switching means when said first hydraulic cylinder means completes its bending stroke,

said third switching means permits electric current flow to a second solenoid valving means associated with a pair of symmetrically disposed second hydraulic cylinder means laterally mounted with respect to said first hydraulic cylinder means, said second solenoid valving means operates to permit the flow of pressurized hydraulic fluid to said second hydraulic cylinder means, a second pressure sensor means provides an electric output signal to a forth switching means upon the completion of the bending stroke of said second hydraulic cylinder means,

said fourth switching means permits the flow of electric current to a third solenoid valving means associated with a pair of symmetrically disposed hold-down means, said third solenoid valving means operates to permit the flow of pressurized hydraulic fluid to said hold-down means causing the same to be arranged in pressurized engagement with said template means and in overlying relation with said tube to constrain vertical movement of the same, a third pressure sensor means provides an electric output signal to a fifth switching means upon the completion of the clamping stroke of said hold-down means,

said fifth switching means is disposed in series with a sixth and seventh switching means and the operation of said switching means permits the flow of electric current to a fourth solenoid valving means associated with a pair of symmetrically disposed third hydraulic cylinder means, wherein each is rigidly mounted to one of said lever means, and operation of said fourth solenoid valving means permits the flow of pressurized hydraulic fluid to said third hydraulic cylinder means, a fourth pressure sensing means provides an electric output signal to said sixth switching means upon the completion of the bending stroke of said third hydraulic cylinder means,

said output signal causes said sixth switching means to commutate such that it directs the flow of current to a fifth solenoid valving means and simultaneously interrupts the flow of electric current to said fourth solenoid valving means rendering said third hydraulic cylinder means inoperative, thereby allowing the same to withdraw from pressurized engagement with said tube, said fifth solenoid valving means is associated with a pair of symmetrically disposed fourth hydraulic cylinder means, each drivingly connected to one of said lever means, wherein operation of said fifth solenoid valving means permits the flow of pressurized hydraulic fluid to said fourth hydraulic cylinder means to cause angular displacement of said lever means,

a displacement sensor means associated with said fourth hydraulic cylinder means provides an electric output signal to said seventh switching means at predetermined intervals of angular displacement of said lever means, said output signal operates to commutate said seventh switching means such that it interrupts the flow of electric current to said fifth solenoid valving means rendering said associated fourth hydraulic cylinder means inoperative, and causing said lever means to remain at said predetermined angular location, and simultaneously directs the flow of electric current to said fourth solenoid valving means to operate said third hydraulic cylinder means to drive said tube against said template means at said successive angular position of each of said lever means,

upon completion of the bending stroke of said third hydraulic cylinder means said output signal of said fourth pressure sensing means operates to commutate said sixth switching means to again reverse the direction of electric current flow to said fifth solenoid valving means, thereby operating to retract said third hydraulic cylinder means and actuate said fourth hydraulic cylinder means, causing successive angular displacement of said lever means,

said incremental angular displacements and cooperating bending operations controlled through the alternating commutation of said sixth and said seventh switching means continues until said displacement sensor means identifies the last predetermined increment of angular displacement of said lever means, wherein said displacement sensor means sends an output signal to said second switching means causing the same to open and thereby interrupt the flow of electric current to said electric circuit means rendering inoperative each of said solenoid valving means, said pressure sensor means, and said displacement sensor means, and thereby cause each of said hydraulic cylinder means and hold-down means to return to their initial inoperative positions for removal of said tube.

7. An apparatus as in claim 3 wherein said control means causes said symmetrically disposed hydraulic cylinders to operate in an alternating manner and comprises:

a first and second of said switching means disposed in series functioning to permit electric current flow to a first solenoid valving means associated with a first hydraulic cylinder means mounted substantially along the line of symmetry of said apparatus, actuation of said first solenoid valving means operates to permit the flow of pressurized hydraulic fluid to said first hydraulic cylinder means, causing the same to drive said tube into pressurized engagement with said template means, a first pressure sensor means associated with said first hydraulic cylinder means provides an electric output signal actuating a third switching means when said first hydraulic cylinder means completes its bending stroke,

said third switching means functions to permit the flow of electric current to a second solenoid valving means associated with a second hydraulic cylinder means laterally mounted with respect to said first hydraulic cylinder means, said second solenoid valving means operates to permit the flow of pressurized hydraulic fluid to said second hydraulic cylinder means, a second pressure sensor means provides an electric output signal actuating a fourth switching means upon the completion of the bending stroke of said second hydraulic cylinder means,

said fourth switching means functions to permit the flow of electric current to a third solenoid valving means associated with a third hydraulic cylinder means symmetrically disposed with respect to said second hydraulic cylinder means, a third pressure sensor means provides an electric output signal actuating a fifth switching means upon completion of the bending stroke of said third hydraulic cylinder means,

said fifth switching means functions to permit the flow of electric current to a fourth solenoid valving means associated with a first hold-down means, said fourth solenoid valving means operates to permit the flow of pressurized hydraulic fluid to said first hold-down means causing the same to be driven into pressurized enagement with said template means and in overlying relation with said tube, a fourth pressure sensor means provides an electric output signal actuating a sixth switching means upon the completion of the stroke of said first hold-down means,

said sixth switching means functions to permit the flow of electric current to a fifth solenoid valving means associated with a second hold-down means symmetrically disposed with respect to said first hold-down means, said fifth solenoid valving means operates to permit the flow of pressurized hydraulic fluid to said second hold-down means, causing the same to be arranged in overlying relation with a portion of said tube symmetrically disposed with respect to that underlying said first hold-down means, a fifth pressure sensor means provides an electric output signal actuating a seventh switching means upon the completion of the stroke of said second hold-down means,

said seventh switching means is disposed in series with an eighth and ninth switching means and the operation of said switching means permits the flow of electric current to a sixth solenoid valving means associated with a fourth hydraulic cylinder means rigidly mounted upon a first lever means, said sixth solenoid valving means permits the flow of pressurized hydraulic fluid to said fourth hydraulic cylinder means, upon completion of the bending stroke of said fourth hydraulic cylinder means a sixth pressure sensor means provides an electric output signal operating to actuate a tenth switching means and commutate an eleventh switching means,

said tenth and eleventh switching means are disposed in series with a twelfth switch means, and the operation of said switching means permits the flow of electric current to a seventh solenoid valving means associated with a fifth hydraulic cylinder means rigidly mounted upon a second lever means symmetrically disposed with respect to said first lever means, said seventh solenoid valving means permits the flow of pressurized hydraulic fluid to said fifth hydraulic cylinder means, upon completion of the bending stroke of said fifth hydraulic cylinder means a seventh pressure sensor means provides an electric output signal operating to commutate said eighth switching means so as to redirect electric current flow from said sixth solenoid valving means to an eighth solenoid valving means, said fourth hydraulic cylinder means mounted upon said first lever means is thereby rendered inoperative and released from pressurized engagement with said tube,

said eighth solenoid valving means is associated with a sixth hydraulic cylinder means drivingly connected to said first lever means and operates to permit the flow of pressurized hydraulic fluid to said sixth hydraulic cylinder means causing the same to translate said first lever means, a first displacement sensor means provides an electric output signal to said ninth switching means at predetermined intervals of angular displacement of said first lever means, upon completion of said first angular displacement of said first lever means said first displacement sensor means provides an output signal operating to commutate said ninth switching means, said commutation renders inoperative said eighth solenoid valving means causing said first lever means to remain idle at said first incremental position, electric current flow is thereby redirected to said sixth solenoid valving means, actuating the same and operating to cause said fourth hydraulic cylinder mean to perform a bending operation at said first incremental position, upon completion of the bending stroke of said fourth hydraulic cylinder means said sixth pressure sensor means provides an electric output signal causing commutation of said eleventh switching means,

said eleventh switching means then redirects electric current flow from said seventh solenoid valving means to a ninth solenoid valving means associated with a seventh hydraulic cylinder means drivingly connected to a second lever means symmetrically disposed with respect to said first lever means, said seventh solenoid valving means is thereby rendered inoperative causing said fifth hydraulic cylinder means mounted upon said second lever means to retract from said tube, said ninth solenoid valving means permits the flow of pressurized hydraulic fluid to said seventh hydraulic cylinder means permitting the same to translate said second lever means,

a second displacement sensor means provides an electric output signal to said twelfth switching means causing commutation of the same at predetermined intervals of angular displacement of said second lever means, upon completion of the first angular displacement of said second lever means said output signal of said second displacement sensor means commutates said twelfth switching means so as to redirect electric current flow to said seventh solenoid valving means and render inoperative said ninth solenoid valving means causing said seventh hydraulic cylinder means and second lever means to remain idle at said first incremental position, said seventh solenoid valving means permits the flow of pressurized hydraulic fluid to said fifth hydraulic cylinder means permitting the same to perform a bending operation at said first incremental position, upon completion of the bending stroke said seventh pressure sensor means provides an output signal causing commutation of said eighth switching means and subsequent retraction of said fourth hydraulic cylinder means and actuation of said eighth solenoid valving means to cause a successive incremental displacement of said first lever means,

said alternating incremental angular displacements and cooperating bending strokes of said first lever means and said fourth hydraulic cylinder means, and said second lever means and said fifth hydraulic cylinder means, continues until said first displacement sensor means and said second displacement sensor means each identify the last predetermined increment of angular displacement of said associated lever means, wherein each respective displacement sensor means produces a final electric output signal causing said second switching means to open upon receipt of both of said signals, and thereby interrupts the flow of electric current to said circuit means, rendering inoperative each of said solenoid valving means, said pressure sensor means, and said displacement sensor means, to cause each of said hydraulic cylinder means and hold-down means to return to their initial inoperative positions for removal of said tube.

8. An apparatus as in claim 3 wherein:

said hydraulic cylinder means drivingly connected to said second set of said displaceable shoe means is mounted in a plane inclined with respect to that of said base plate means,

said base plate means comprises a middle section and two symmetrically disposed end sections arranged in a manner such that said end sections may be laterally adjusted to conform to varying lengths and configurations of said tube,

said template means comprises separable sections corresponding with said sections of said base plate means,

said second set of movable shoes have fixedly attached thereto a flexible strip extending substantially parallel to said tube length.