Method of producing a bent part and bending machine for performing the method

Abstract

A method produces a bent part from an elongate workpiece, in particular from a wire or a tube from round, flat, or profiled material, by a bending machine, the workpiece is fed to a bending unit of the bending machine, wherein the bending unit has a bending head which by a Z-drive is displaceable in a manner parallel with a bending head axis and has a bending tool which by a bending drive is rotatable about a bending axis. A fed portion of the workpiece by operating movements of the bending head is formed to a two-dimensionally or three-dimensionally bent part.

Claims

1. A bending machine for producing a bent part from an elongate workpiece comprising: a bending unit having a bending head which, by a Z-drive, is displaceable in a manner parallel with a bending head axis and has a bending tool which, by a bending drive, is rotatable about the bending axis; and a cutting installation for severing a finished bending part from the workpiece in a cutting operation, said cutting installation being separate from the bending head, wherein a movable component of the cutting installation for transmitting forces and movements is coupled exclusively to the Z-drive by a transmission installation such that the cutting installation is activatable exclusively by way of the Z-drive, and the transmission installation is configured such that a linear movement of the bending head across a first stroke portion between a bending position and a relocating position does not cause any movement of the movable component of the cutting installation that is coupled to the Z-drive.

2. A bending machine for producing a bent part from an elongate workpiece comprising: a bending unit having a bending head which, by a Z-drive, is displaceable in a manner parallel with a bending head axis and has a bending tool which, by a bending drive, is rotatable about the bending axis; and a cutting installation for severing a finished bending part from the workpiece in a cutting operation, said cutting installation being separate from the bending head, wherein a movable component of the cutting installation for transmitting forces and movements is coupled exclusively to the Z-drive by a transmission installation such that the cutting installation is activatable exclusively by way of the Z-drive, and the transmission installation has a control curve which converts a uniform movement of the bending head along the bending head axis to a non-uniform movement of the movable component of the cutting installation that is coupled to the Z-drive.

3. The bending machine as claimed in claim 2, wherein the control curve has a first curve portion which is oriented such that a linear movement of the bending head in a manner parallel with the bending head axis across a first stroke portion between a bending position and a relocating position does not cause any movement of the movable component of the cutting installation that is coupled to the Z-drive, and a second curve portion is contiguous to the first curve portion, said second curve portion being oriented obliquely to the first curve portion such that a further linear movement of the bending head in a manner parallel with the bending head axis beyond the relocating position causes a movement of the movable component of the cutting installation that is coupled to the Z-drive.

4. The bending machine as claimed in claim 2, wherein the movable component of the cutting installation is a lever which is rotatable about a lever axis.

5. The bending machine as claimed in claim 2, further comprising a drawing-in installation for drawing off workpiece material from a material supply and feeding the workpiece material to the bending unit, wherein the cutting installation is disposed between the drawing-in installation and the bending head.

6. A method of producing a bent part from an elongate workpiece using a bending machine, the method comprising: feeding workpiece material to a bending unit of the bending machine, wherein the bending unit has a bending head which, by a Z-drive, is displaceable in a manner parallel with a bending head axis and has a bending tool which, by a bending drive, is rotatable about a bending axis; forming a fed portion of the workpiece material by operating movements of the bending head into a two-dimensionally or three-dimensionally bent part; and severing the bent part from the workpiece material in a cutting operation to obtain a finished bent part by a cutting installation that is separate from the bending head, wherein the cutting installation is activated exclusively by an operating movement of the bending head in a direction parallel to the bending head axis by a transmission installation, and the transmission installation has a control curve which converts a uniform movement of the bending head along the bending head axis to a non-uniform movement of the movable component of the cutting installation that is coupled to the Z-drive.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages and aspects are derived from the description hereunder of preferred examples explained hereunder by the figures.

(2) FIG. 1 shows an oblique perspective view of a bending machine according to one example, seen from the front side equipped with a bending head.

(3) FIG. 2 shows a plan view of a fragment of the bending machine from FIG. 1, seen in the direction parallel to the bending head axis of the bending head.

(4) FIGS. 3a, 3b, 4a, 4b, 5a and 5b show various operating positions of the bending head and of the cutting installation coupled thereto.

DETAILED DESCRIPTION

(5) Examples will be explained hereunder by a computer numerically controlled bending machine 100 specified for bending wire. FIG. 1 shows an oblique perspective front view of the single-head bending machine. FIG. 2 shows a plan view of a fragment of the bending machine from FIG. 1, seen in the direction parallel with the bending head axis of the bending head of the bending machine.

(6) The bending machine 100 as a wire bending machine provides a portion of an elongate workpiece 110 in the form of a wire having a preferably round cross section with one or a plurality of bends in one or a plurality of bending planes by cold forming. Wires having a flat or profiled cross section can also be bent.

(7) The bending machine 100 in the example has an orthogonal machine coordinate system MK having a vertical z-axis and a horizontal x-axis and y-axis, the machine coordinate system MK being identified by the lowercase letters x, y, and z. In the illustrated example, the x-axis runs in a manner parallel with the workpiece axis 112 of the not yet bent workpiece. The machine axes which are driven in a controlled manner and each of which is identified by uppercase letters (for example, A, C, Z, etc.) are to be differentiated from the coordinate axes.

(8) All of the drives for the machine axes are electrically connected to a control installation (not illustrated) which contains inter alia the power supply to the drives, a central computing unit, and data storage units. The movements of all of the machine axes are variably controlled with the aid of the control software active in the control installation to generate a coordinated movement of the elements participating in the bending procedure. A display and operating unit 130 connected to the control installation serves as an interface to the machine operator.

(9) For a bend to be generated, an initially straight workpiece portion is moved to an initial position in the engagement region of the bending head 180. To this end, the operation proceeds from a comparatively long workpiece supply (coil) in accordance with the illustrated example.

(10) To this end, the bending machine has a drawing-in installation (not visible in FIG. 1) equipped with drawing-in rollers and which by way of a numerically controlled feeding rate profile in the horizontal direction (in a manner parallel with the x-direction) can draw in or feed, respectively, successive wire portions of a wire emanating from a wire supply and possibly guided through an optional straightening unit into the region of the bending head 180. The wire at the exit side is guided through a tubular wire guide and exits in the horizontal infeeding direction. The feeding (the drawing-in movement) is stopped once the wire reaches an initial position. The linear machine axis for the infeeding is referred to as the C-axis and has a motor (not illustrated).

(11) The wire when feeding exits from the front end of the wire guide, thereafter runs through the region of a cutting installation 150 (yet to be explained later) into the engagement region of the bending head 180. The cutting installation 150 is disposed between the drawing-in installation and the bending head.

(12) A rotation of the workpiece about the workpiece longitudinal axis, for example, for changing the bending plane, is generated by way of the rotary drive of the A-axis. On account thereof, the drawing-in installation in its entirety can be rotated conjointly with the straightening unit about an axis which is parallel with the x-axis.

(13) The bending head 180 has an internal tool part 182 which is stationary during the bending procedure and in the plan view (cf. FIG. 2) has a cylindrical external contour. The tool part on the upper side thereof supports a plurality of exchangeable bending mandrels of dissimilar diameters, of which in each instance one (for example, the bending mandrel 183) can be moved to an operating position close to the workpiece axis to serve as an internal support of the workpiece portion in the bending procedure. The external diameter of the bending mandrel 183 utilized establishes the bending radius of the bend to be generated, thus the curvature radius of the bend. A separate drive output 187 (servomotor and gearbox) is provided for rotating the internal tool part 182 about the bending head axis 185 for changing over between different bending mandrels. The corresponding machine axis is also referred to as the mandrel axis.

(14) Furthermore, the bending head 180 has a bending tool 184 which is rotatable in relation to the internal tool part and is provided for engaging laterally on a portion of the workpiece material to be bent. The bending tool 184 on the upper side thereof supports a bending pin 186 and by a bending drive 189 (servomotor and gearbox) controlled by the control installation is rotatable about a bending axis which here coincides with the bending head axis 185. The orientation of the bending axis establishes the orientation of the bending plane which lies to be orthogonal to the bending axis and includes the workpiece axis 112.

(15) The bending unit having the bending head 180 in many examples is pivotable as an entity about an axis that runs in a manner parallel to the x-axis such that the bending axis 185 can be aligned selectively to be vertical (parallel with the z-direction) or to be oblique thereto in an inclined position. In the example illustrated, the bending unit as an entity is disposed at a fixed angle in relation to the vertical z-axis. It is possible for the angle be 0°, thus z=Z. An inclination of 20° to 30° in relation to the vertical is usual. As has been mentioned, a manual or motorized pivoting installation is also possible. It is important herein that the bending unit is pivoted as an entity, thus including the bending axis and the Z-axis. To this end, the tool elements of the bending head are assembled in a solid support 193 which in pivotable variants can be guided in arcuate guides on the front wall of the machine base 102. A metallic table top 192 of a bearing table 190 is assembled on the upper side of the support, the planar upper side of the bearing table 190 in each position of the bending head lies slightly below the level of the workpiece axis 112. The bearing table serves as a bearing for those portions of a bending part that protrude beyond the bending head, and as a chute by way of which the finished bent parts after having been severed from the material supply can slide laterally into a collection container.

(16) Further details relating to the construction and the function of the bending machine 100 can be understood particularly readily by FIGS. 2 to 5b. FIG. 2 herein shows a plan view of a fragment of the bending machine from FIG. 1, seen in the direction parallel with the bending head axis 185 of the bending head 180. The cutting installation 150 which is disposed between the drawing-in installation for the workpiece (not illustrated in FIG. 2) and the bending head 180 can also be seen herein. FIGS. 3a to 5b show views of the bending machine in the region of the bending head 180 and of the cutting installation 150, seen in a direction parallel with the x-axis of the machine coordinate system, or parallel with the infeeding direction of the workpiece to be bent, respectively.

(17) The cutting installation 150 is an installation separate from the bending head 180 and which has the tools (cutting tools) required for severing the workpiece. The cutting tools are those components of the cutting installation that are provided for direct contact with the workpiece, or for engaging on the workpiece, respectively. No tools of the cutting installation are attached to the bending head. Degrees of freedom in terms of the constructive concept and arrangement of the cutting installation 150 in relation to the bending head 180 result in the use of a cutting installation that is separate from the bending head.

(18) FIG. 3b shows the components of the bending machine in a first position which is also referred to as the bending position. The bending head 180 in this first position is situated in the terminal position thereof that is closest to the workpiece and in which the bending pin 186 of the bending tool is introduced into the workpiece plane such that a rotation of the bending tool can cause a bend on the workpiece. As can be seen in the enlarged detail in FIG. 3a, the cutting installation 150 herein is situated in an opened position without any cutting engagement on the workpiece. Feeding of workpiece material in the infeeding direction (parallel with the x-axis, or with the workpiece longitudinal axis 112, respectively) is possible in the opened position.

(19) FIG. 4b shows the same components in a second position which here is also referred to as the relocating position. The bending head 180 herein is situated in a position which is slightly retracted (for example, by approx. 10 mm to approx. 20 mm, possibly even more or less, depending on the wire diameter) in relation to the bending position and enables a relocation of the bending pin, thus a rotation of the bending tool without any engagement on the workpiece. As can be seen in FIG. 4a, the cutting installation continues to be in an opened position.

(20) FIGS. 5a and 5b finally show a configuration or position, respectively, in which the bending head 180 is situated in the lowered position thereof which is retracted farthest from the workpiece. The cutting installation 150 is activated in the movement from the relocating position to the lowermost position such that the finished bent part is severed from the fed workpiece portion. Structural components which enable this advantageous functionality are explained in more detail hereunder.

(21) The bending head 180, or the components thereof, respectively, are assembled on a linearly displaceable slide 200 also referred to as the bending slide. The displacement direction of the slide runs to be perpendicular to the infeeding direction of the wire, thus to be perpendicular to the x-direction of the machine coordinate system. The orientation of the bending slide establishes the orientation of the bending head axis 185 in relation to the infeeding direction of the workpiece. The bending head as an entirety can be linearly displaced in a manner parallel with the bending head axis 185. That numerically controlled machine axis that causes the linear movement of the bending head in a manner parallel with the bending head axis is referred to here as the Z-axis. The associated drive which here is referred to as the Z-drive comprises a crank mechanism 210 which is rotatable about a rotation axis that runs in a manner parallel with the x-axis. The slide 200 is coupled to the crank mechanism 210 of the Z-drive by way of a transmission rod 220.

(22) A plate-shaped portion 205 in which an angular groove, or a groove curve 165, is incorporated is attached to the slide 200 on the side of the lever 160, the slide 200 enabling the linear movement of the bending head. The groove, also referred to as the control groove, can be subdivided into a first portion 165-1 which is aligned to be parallel with the bending head axis 185, and a second portion 165-2 which is set to be oblique in relation to the first portion, or the bending head axis, respectively. The first portion and the second portion are each substantially rectilinear and in relation to one another enclose an acute angle of approx. 20° to 40°. The second portion 165-2 in terms of length is more than double the first portion 165-1.

(23) The cutting installation 150 is constructed such that a finished bent part in a cutting operation can be severed from the fed workpiece portion in the manner of a shear cut. A first blade 152 of the cutting installation 150 is assembled to be fixed on the machine with the aid of an adjustable blade support, that is to say to be fixedly assembled in relation to the machine base of the bending machine. The first blade 152 interacts with a second blade 154 assembled to be adjustable on a movable component 160 of the cutting installation. The exchangeable blades 152, 154 are the cutting tools of the cutting installation 150. The cutting gap 155 which defines the separation plane is situated between the blades. This shear cut is carried out when the second blade 154 in relation to the first blade 152 in the y-direction moves (on an arc) to be substantially parallel with the x-y plane.

(24) The movable component 160 which supports the second blade 154 is a lever 160 (also referred to as the cutting lever 160) which is mounted to be pivotable about a rotation axis 162 which is fixed on the machine and runs to be parallel with the x-direction. The support structure for the second blade 154 is situated on the upper side of the lever 160 to be close to the rotation axis 162. A longer angular lever arm 164 protrudes downward to be substantially parallel with or at an acute angle to the bending head axis 185. A cam roller 230 is mounted to be rotatable on that end portion of the lever 160 facing away from the rotation axis 162. The cam roller 230 is guided in the angular groove 165 (groove curve, control groove) on the bending slide.

(25) The cam roller 230 attached to the lever 160, and the angular groove 165 on the bending slide 200, are substantial component parts of a fully mechanical transmission installation 250 which for transmitting forces and moments couples a movable component of the cutting installation 150, specifically the lever 160 having the second blade 154 fastened thereon, to the Z-drive of the bending head 180 such that the cutting installation 150 can be activated exclusively by way of the Z-drive. The cutting installation 150 as well as the bending head 180 are thus activated by one and the same drive (the Z-drive) such that a separate drive is not required for the cutting installation.

(26) The construction and the function of the example can also be described as follows.

(27) The base part of the cutting installation 150, specifically a so-called cutting support, links the cutting installation 150 to the machine body of the bending machine and supports the rotation axis 162 for the lever (cutting lever) 160 as well as the first blade 152 which is assembled to be fixed on the machine. The lever (cutting lever) 160 is mounted to be rotatable on the cutting support. The articulation of the lever 160 takes place by way of the cam roller 230 fastened to the free lever end. The cam roller 230 runs in an angular groove curve 165. The groove curve 165 is fastened to the slide 200 (bending slide) and conjointly with the slide 160 moves up and down in a manner parallel to the bending head axis 185. This is the operating movement of the Z-axis of the drive system of the bending machine.

(28) The groove curve 165 has a straight first portion 165-1 which runs to be parallel to the Z-axis movement, and a second portion 165-2 which runs at an angle in relation to the Z-axis movement. The two respective straight sections, or portions, respectively, of the groove curve are connected by a curved part that runs according to a principle of movement.

(29) The Z-axis moves the bending head 180 up and down in a manner parallel with the bending head axis 185. The Z-axis in the example is driven by a crank, as is illustrated in the drawings, or by way of a ball screw spindle. Alternatively, the Z-axis can also be driven by way of any other solution suitable for linear drives.

(30) In the first position (bending position) shown in FIG. 3b the bending head 180 is situated in a bending position in terms of the Z-axis. The lever 160 (cutting lever) is in the position opened for the passage of a wire (see detail 3a).

(31) In the configuration of FIGS. 4a and 4b the bending head 180 in terms of the Z-axis is situated in a position for relocating the bending pin 186. This axial position is referred to as the relocating position. The bending finger in the relocating position can be guided below the wire, and the bending direction can thus be changed. It can be seen that the cam roller 230, when changing from the bending position to the relocating position, within the first portion 165-1 of the groove curve 165 has moved only in a manner linearly parallel with the bending head axis. No pivoting movement has thus been caused on the lever 160 such that the blades of the cutting installation continue to be situated in the opened position. In other words, the relative position of the blades of the cutting installation has not changed when transitioning from the bending position to the relocating position. In the normal bending operation, which possibly includes a multiple axial movement of the bending head from the bending position to the relocating position, the cutting installation is thus practically decoupled from the Z-drive.

(32) Once the bending procedure has been completed after all envisaged bending operations for producing the bent part have been carried out on the workpiece, the cutting operation can be initiated. To this end, the bending head by the Z-drive is moved back beyond the relocating position to the maximum retracted position (cutting position). FIGS. 5a and 5b show a situation in which the bending head in terms of the Z-axis is situated in the third position for cutting the workpiece. The cam roller 230 on the displacement path from the relocating position to the retracted position by way of the transition portion between the first portion 165-1 and the second portion 165-2 moves into the second portion 165-2 and then along the second portion. The lever 160, by virtue of the oblique profile of the second portion 165-2, is pivoted ever more outward during the retraction movement such that the second blade 154 in a cutting movement is displaced relative to the first blade 152 and the wire is sheared off. The cutting procedure has been completely performed when the cutting lever is situated in the maximum deflected position shown in FIGS. 5a and 5b.

(33) For a further bent part to be generated, the bending head by the Z-axis has to be mandatorily displaced upward again, at least to the relocating position so that the movable blade again releases the opening of the stationary blade.

(34) The bending head 180 in this construction for relocating the bending tool in terms of the Z-axis thereof can be moved up and down without the lever 160 (cutting lever) moving. The bent part can be bent while the bending head moves in this region. When the bending procedure has ended and the bent part is to be severed by activating the cutting installation 150, the bending head moves beyond the relocating position further downward until the workpiece (the wire) has been cut off. The bent part can then drop out of the bending machine. The dropping of the bending part is facilitated on account of the comparatively low position of the bending head 180, thus on account of the very retracted position of the bending head, because the probability of the bending part catching on the bending head is significantly reduced on account thereof.

(35) A complete machine axis, or a complete machine drive for the cutting installation, can thus be saved. At the same time, the movement of the Z-axis for relocating the tool continues to be possible without the cutting lever moving by way of the coupling action.