GB1580333A - Bending apparatus - Google Patents

Abstract

Assigned to an upper roll (3) are two side rolls (4) and one or two abutments (6) for guiding and supporting the shorter circular-arc edge of the sheet-metal blank (5). The abutments (6) are designed in such a way that they direct the supporting force or a component of the latter into an adjustable counter-pressure device (8) safeguarded against overload. The abutment (6) can be arranged between or to the outside of the side rolls. In order to ensure that the sheet-bending process is carried out in a particular, desired working region of the rolls, the abutment (6) can be adjusted parallel to the rolls on cross-members (9) or rocker levers, as a guide for the sheet-metal blank. It is thereby possible to ensure that the sheet-bending operation takes place in the working region of the rolls in which both bending-roll adjusting drives are subjected uniformly to forces. <IMAGE>

Description

(54) BENDING APPARATUS (71) We, HINRICHS GESELLSCHAFT MtT BESCHRÄNKTER HAFTUNG a Joint Stock Company organised under the laws of Germany (Fed. Rep.) of D-2054 Geestkacht, Germany (Fed. Rep.) do hereby declare the invention for which we pray that a Patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: The invention relates to an apparatus for bending sheet metal blanks in the shape of a segment of a circular ring to form conical parts on a plate-bending machine, consisting of an upper roller or a pair of central rollers and two side rollers as well as of one or two abutments for guiding and supporting the shorter edge of the sheet metal blank, which wedge is in the shape of an arc of a circle. The plate-bending machine can be of any construction, i.e. can be equipped both with three as well as four rollers for bending metal sheets and it is immaterial which of the rollers can be adjusted in any direction and can be tilted or moved for conical bending and which are provided with a rotary drive for the purpose of conveying the metal sheet.

Conical bending on plate-being machines causes problems because the feed movement of the driven rollers at any point of the sheet metal blank naturally takes place at rightangles to the axis of the rollers, whereas the bending lines of conical parts extend in the manner or rays from the central point of the segment of the circular ring or towards the point of intersection of the surface lines of the cone. This means that the speed of passage at the larger outer radius of the sheet metal blank must be accelerated with respect to the conveying speed of the rollers or the speed of passage at the smaller inner radius must be retarded.

In a three roller plate-bending machine, the known apparatus which guide the sheet metal blank by force during the bending operation, consist of two abutment rollers or pins which are seated on the machine uprights or on the bearings of the adjustable rollers (German Auslegeschrift 1 269 084) or in a four roll platebending machine, of a sliding shoe which is located centrally between the journal pins of bending rollers, i.e. on the bearing of the lower roller (German Gebrauchsmuster 6913573).

In a three roller plate-bending machine, the provision of an entry plate as an abutment is likewise known, which plate is located on the inner side of the machine column and can be lowered for removing the finished workpiece from the working region.

These known apparatus have the following drawbacks: The edge of the metal sheet supported at the inner radius of the sheet metal blank causes high support pressure on the abutment, which is dependent on the frictional forces between the metal sheet and the bending rollers. When an admissible abutment pressure is exceeded, the edges of the metal sheet are inadmissibly compressed or the abutment is destroyed or damaged. An overload of this type occurs very frequently in practice, since the frictional forces are dependent on the thickness of the sheet metal, on the width of the sheet metal, the quality of material, the diameter of the cone and on the very different frictional values between the sheet metal and bending rollers and thus cannot be predetermined.

The horizontal forces occurring in the longitudinal direction of the bending rollers acting on the one hand on the abutment and on the other hand on the mounting of the bending rollers can force the machine up rights apart, which can only be prevented by additional and expensive strengthening of the machine frame.

The range of conical shapes which can be produced on plate-bending machines of known construction is limited considerably, because the abutments are ararnged at one side in a stationary manner at the ends of the bending rollers. Due to this, only those blanks can be bent which do not abut against the uprights or upper roller bearing of the machine at the time of bending. This is particularly true for large machines.

According to the present invention there is provided a machine for bending arcuate sheet metal blanks into conical form, comprising a plurality of rollers defining a feed path there between, drive means for driving at least one of said rollers to convey successive blanks along said feed path thereby bending them into conical form, movable abutment means positioned at one side of the feed path for engagement by the shorter arcuate edge of each blank, whereby the abutment means is subjected in use to a deflection force tending to deflect the abutment means away from the feed path, adjustable force exerting means for exerting a predetermined retaining force to counteract said deflection force and retain the abutment means in position, and switch means for stopping the drive means upon movement of said abutment means when the deflection force exceeds the retaining force.

The abutment means may comprise one abutment position between entry and discharge side rollers defining said feed path or two abutments in flanking relationship with said side rollers.

The abutment means may be arranged for pivotal deflection movement on a fixed cross bar extending between uprights of the machine frame, said force exerting means acting directly on the abutment means to prevent said pivotal movement during normal operation.

Alternatively, the abutment means may be muonted between uprights of the machine frame on a rocker arm pivoted at one end and acted upon at its other end by said force exerting means.

In a further alternative construction, the abutment means may be mounted on a lengthwise movable cross bar extending between uprights of the machine frame and acted upon at one end by said force exerting means, the abutment means being adapted to be withdrawn transversely of the cross bar.

Preferably, the abutment means is adapted to be fixed in a selected position along the cross bar or rocker arm.

The force exerting means may comprise a spring or fluid pressure operated means.

The invention will now be further described by way of example only with reference to the accompanying drawings, in which: - Figure 1 is a side view of a plate-bending machine with an abutment which is mounted to move on a stationary cross bar.

Figure 2 is a side view of a plate-bending machine with an abutment which is mounted to move on a rocking lever.

Figure 3 is a side view of a plate-bending machine with an abutment which is mounted to move on a movable cross bar, the abutment being able to be withdrawn and the cross bar is provided with a counterpressure device.

Figure 4 is a cross section through the bending rollers of a three or four roller platebending machine with two abutments, which are mounted and able to tilt on a movable cross bar.

Figure 5 is a plan view of a plate-bending machine as shown in Figures 1 to 3 equipped with one abutment.

Figure 6 is a plan view of a plate-bending machine as shown in Figures 1 to 4 when equipped with two abutments.

The basic construction of plate-bending machines consists of two machine uprights 1, 2, in each of which three or four bending rollers are mounted, depending on the construction. Associated with an upper roller 3 are two side rollers 4, which are possibly supplemented by a lower roller 3a, according to Figure 4.

Depending on the construction, the bending rollers are able to move vertically, horizontally or obliquely or can be mounted in a stationary manner and provided with a rotary drive for the purpose of conveying the sheet metal.

Furthermore, the moving bending rollers can be tilted in order to be able to make conical parts from sheet metal blanks in the shape of segments of a circular ring.

The removal of a finished bent cone from the machine is possible by tilting the bearing la of the upper roller 3.

Serving for positive guidance of the sheet metal blank 5 is at least one abutment 6, against which the sheet metal blank 5 is supported on the small inner radius Sa. The abutments 6 can be located between or beside the entry and discharge side rollers 4.

The abutment 6 is constructed as an angle lever and is mounted to rotate at the pivot 7.

A counterpressure device 8 exerts an adjustable force which keeps the abutment in the working position by acting in opposition to the deflection force exerted by the metal blank 5. If the deflection force becomes so great that the pre-est counter-force is exceeded, the counterpressure device 8 can withdraw and switch the machine off by way of a contact which is not shown. The stroke of the counterpressure device 8 is appropriately such that lowering of the abutment out of the working region is possible.

Furthermore, the abutment is mounted to move by the amount "a" for example, on a stationary cross bar 9 in the longitudinal direction of the bending rollers. Displacement and fixing in the desired position can be undertaken by means of conventional adjusting mechanisms, such as a spindle, rack, chain drive, locking bolt and the like, which are not shown.

In the embodiment according to figure 2, the abutment 6 is mounted to move on a rocking lever 10, which is pivoted io the machine upright 2 at the pivot 11 and due to the counterpressure device 8a keeps the abutment in the working position.

The embodiment according to figure 3 shows the abutment 6 which is mounted to move on a cross bar 12 moving in guides 1313. In this case, the movement functions are separated in that the counterpressure device 8b keeps the movable cross bar 12 and thus the abutment 6 mounted thereon, in the working position, whereas an additional withdrawal device 14 makes it possible to withdraw the abutment 6 from the working region or to bring it into any position within the range of travel of the withdrawal device.

A further embodiment is shown in figure 4, which is a vertical section through the roller of a three or four roller platebending machine, where one or two abutments 6 are mounted to move respectively on a stationary or movable cross bar 9, 12 or on a rocking lever 10 in the longitudinal direction of the rollers 3, 3a, 4.

In this case, the abutments 6 are located adjacent the side rollers 4 and are constructed to rotate, so that they can be swung out of the working region or can be brought into a desired working position inside the field of traverse.

Figures 5 and 6 are plan views showing the position of the abutments in single abutment and double abutment machines.

WHAT WE CLAIM IS: 1. A machine for bending arcuate sheet metal blanks into conical form, comprising a plurality of rollers defining a feed path therebetween, drive means for driving at least one of said rollers to convey successive blanks along said feed path thereby bending them into conical forms, movable abutment means positioned at one side of the feed path for engagement by the shorter arcuate edge of each blank, wehreby the abutment means is subject in use to a deflection force tending to deflect the abutment means away from the feed path, adjustable force exerting means for exerting a predetermined retaining force to counteract said deflection force and retain the abutment means in position, and switch means for stopping the drive means upon movement of said abutment means when the deflection force exceeds the retaining force.

2. A machine as claimed in claim l, where- in the abutment means comprises one abutment positioned between entry and discharge side rollers defining said feed path.

3. A machine as claimed in claim 1, wherein the abutment means comprises two abutments in flanking relationship with entry and discharge side rollers defining said feed path.

4. A machina as claimed in any one of the preceding claims, wherein the abutment means is arranged for pivotal deflection movement on a fixed cross bar extending between uprights of the machine frame, said force exerting means acting directly on the abutment means to prevent said pivotal movement during normal operation.

5. A machine as claimed in any one of claims 1 to 3, wherein the abutment means is mounted between uprights of the machine frame on a rocker arm pivoted at one end and acted upon at its other end by said force exerting means.

6. A machine as claimed in any one of claims 1 to 3, wherein the abutment means is mounted on a lengthwise movable fross bar extending between uprights of the machine frame and acted upon at one end by said force exerting means, the abutment means being adapted to be withdrawn transversely of the cross bar.

7. A machine as claimed in any one of claims 4 to 6, wherein the abutment means is adapted to be fixed in a selected position along the cross bar or rocker arm.

8. A machine as claimed in any one of the preceding claims, wherein the force exerting means comprises a spring or fluid pressure operated means.

9. A machine for bending arcuate sheet material blanks into conical form, sub stantially as herein described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. working position, whereas an additional withdrawal device 14 makes it possible to withdraw the abutment 6 from the working region or to bring it into any position within the range of travel of the withdrawal device. A further embodiment is shown in figure 4, which is a vertical section through the roller of a three or four roller platebending machine, where one or two abutments 6 are mounted to move respectively on a stationary or movable cross bar 9, 12 or on a rocking lever 10 in the longitudinal direction of the rollers 3, 3a, 4. In this case, the abutments 6 are located adjacent the side rollers 4 and are constructed to rotate, so that they can be swung out of the working region or can be brought into a desired working position inside the field of traverse. Figures 5 and 6 are plan views showing the position of the abutments in single abutment and double abutment machines. WHAT WE CLAIM IS:

1. A machine for bending arcuate sheet metal blanks into conical form, comprising a plurality of rollers defining a feed path therebetween, drive means for driving at least one of said rollers to convey successive blanks along said feed path thereby bending them into conical forms, movable abutment means positioned at one side of the feed path for engagement by the shorter arcuate edge of each blank, wehreby the abutment means is subject in use to a deflection force tending to deflect the abutment means away from the feed path, adjustable force exerting means for exerting a predetermined retaining force to counteract said deflection force and retain the abutment means in position, and switch means for stopping the drive means upon movement of said abutment means when the deflection force exceeds the retaining force.

2. A machine as claimed in claim l, where- in the abutment means comprises one abutment positioned between entry and discharge side rollers defining said feed path.

3. A machine as claimed in claim 1, wherein the abutment means comprises two abutments in flanking relationship with entry and discharge side rollers defining said feed path.

4. A machina as claimed in any one of the preceding claims, wherein the abutment means is arranged for pivotal deflection movement on a fixed cross bar extending between uprights of the machine frame, said force exerting means acting directly on the abutment means to prevent said pivotal movement during normal operation.

5. A machine as claimed in any one of claims 1 to 3, wherein the abutment means is mounted between uprights of the machine frame on a rocker arm pivoted at one end and acted upon at its other end by said force exerting means.

6. A machine as claimed in any one of claims 1 to 3, wherein the abutment means is mounted on a lengthwise movable fross bar extending between uprights of the machine frame and acted upon at one end by said force exerting means, the abutment means being adapted to be withdrawn transversely of the cross bar.

7. A machine as claimed in any one of claims 4 to 6, wherein the abutment means is adapted to be fixed in a selected position along the cross bar or rocker arm.

8. A machine as claimed in any one of the preceding claims, wherein the force exerting means comprises a spring or fluid pressure operated means.

9. A machine for bending arcuate sheet material blanks into conical form, sub stantially as herein described with reference to and as illustrated in the accompanying drawings.