Abstract: Systems and methods for bending a material to a target resultant bending parameter using a bend forming tool are disclosed. The systems and methods receive values for parameters of properties of the material and of a bending process to be performed by the bend forming tool, creating or retrieving a calibration curve relating input bending parameter and resultant bending parameter based on the values from a database of calibration curves, determining a first springback compensated input bending parameter based on the target resultant bending parameter using the calibration curve, inputting the first springback compensated input bending parameter to the bend forming tool, and in a first step of bending the material, bending the material to the first springback compensated input bending parameter by applying the bending process using the bend forming tool.

Abstract: A method of manufacturing a press-formed product includes: capturing the amount of warp in a sheet to be pressed separately for each sheet; and using a die 6, a punch 7, and a movable mold part to press-form the sheet into a press-formed product. During press-forming, the initial position of the movable mold part 9 relative to the die 6 or punch 7 is controlled depending on the amount of warp in the sheet.

Abstract: A method and apparatus for bending an elongate member. A plastic force may be applied to the elongate member. The plastic force may be configured to cause the elongate member to bend with a plastic deformation. The plastic force may be reduced to an elastic force that is applied to the elongate member after the plastic force causes the elongate member to bend with the plastic deformation.

Abstract: A bending machine having: a punch and a die for bending a sheet-shaped work; pressurizing means which pressurizes the work in a space between the punch and the die by vertically moving a ram; inputting means (23) which inputs die information on the punch and the die, material information on the work and bending information; a database (25) which stores data on a pressure per unit length required for bending the work; calculating means (29) which calculates a pressure necessary for the pressurizing means based on various information inputted from the inputting means (23) and on the data on the pressure stored in the database (25); and controlling means (31) which controls the pressurizing means based on a result of calculation by the calculating means (29).

Abstract: The invention provides a hydroforming apparatus for forming a length of tube. A hydroforming press includes an upper platen and a lower plate. A first die set is provided for forming a first lengthwise portion of the tube and a second die set provided adjacent the first die set which forms a second lengthwise portion of the tube. A first pivot acts between a first and second upper die so that the second upper die can be pivotally adjusted on the upper platen relative to the first upper die. A second pivot acts between a first and second lower die so that the second lower die can be pivotally adjusted on the lower platen relative to the first lower die. A die insert is provided having an upper die insert and a lower die insert that define upper and lower insert cavities that connect together the first and second cavity portions of the upper die set and the lower die set. This die insert is removably mounted as needed to accommodate the pivotal adjustment between the first and second die sets.

Abstract: A method of mechanically treating alloy metal surgical needles to improve bending strength is disclosed. The needles are curved and reverse-curved in this method to improve bending strength.

Abstract: A bending angle detecting device for a workpiece used in a bending machine that bends the workpiece in cooperation of upper and lower tools. The bending angle detecting device has a detector which includes a casing and which can detect a bending angle of the workpiece with the casing fixed in contact with a contact portion of the lower tool.

Abstract: With a method according to the invention for free bending, a workpiece to be machined, such as a sheet metal plate, is brought into contact with a bending edge of a lower die. A bending punching tool is moved opposite to the lower die, such that the sheet metal plate is bent by the punching tool in terms of generating a predetermined target bending angle across the bending edge. In this case, the achieved bending angle is measured at least after a first bending process and the bending force to be applied and the measuring curve resulting therefrom are determined during the bending process as a function of the traverse path of the bending punching tool.

Abstract: A method of bending a metal object, such as a tube, is provided that uses real time, closed-loop feedback of the actual springback of the object in order to modify the applied bending force or preprogrammed bending coordinates so that the final desired bend geometry is achieved. The variability of springback from object to object is thus accounted for and the number of objects that must be scrapped due to incorrect bends (over bend or under bend) is reduced. The method is carried out using an apparatus such as a rotary draw bender with a measuring device operable to measure actual bend coordinates of metal objects bent by the bender. A controller is operatively connected to the bender and the measuring device and is configured to control the bender to bend the metal objects at least partly based on measured bend coordinates provided by the measuring device.

Abstract: Method of correcting a bending operation performed by a press brake, the bottom beam of which contains deformation compensation cylinders, in which a calibration nomogram is pre-recorded using very short calibration pieces, this nomogram establishing a correspondence between the forces measured at the side frames and the pressures applicable to the compensation cylinders in order to keep the bottom beam substantially straight. During a subsequent bending operation, pressure values resulting from this nomogram are applied to the compensation cylinders according to the forces measured at the side frames. A bottom dead center is recalculated by taking account of the deformation of the top beam, the deformation of the side frames, the actual length and thickness of the piece, and the spring effect.

Abstract: A device for monitoring an area of coverage on a work tool may comprise a lighting unit, a camera, and an evaluation unit. The lighting unit may be adapted to emit light rays for illuminating the area of coverage. The camera may be adapted to detect two-dimensional images of the area of coverage, and the camera may comprise receiving elements arranged linearly. The evaluation unit may be coupled to the camera to evaluate the output signals of the receiving elements to determine a distance value for each receiving element based on the light rays emitted by the lighting device and reflected back from the area of coverage. The evaluation unit may have at least one switching output coupled to the work tool to activate the work tool such that the work tool is operational only if no object is located in the area of coverage.

Abstract: A pipe bending system employing a sensing and indicating system that provides feedback to an operator regarding the position of components of the pipe bending system, such as the pin-up shoe and the stiffback. Apparatus for retrofitting a sensing and indicating system to existing pipe bending apparatus.

Abstract: A method for processing sheet metal includes processing and forming a sample and a blank on a work while leaving a microjoint part in a blanking process. The method also includes detecting at least one of a plate thickness of the work in an optional position and a spring-back amount of the sample during bending. Information of at least one of the plate thickness and the spring-back amount is transmitted to a controller of a bending machine in a bending process after the blanking process. Bending is performed by calculating a ram control value in bending using data of at least one of the transmitted plate thickness and the spring-back amount.

Abstract: A method of determining springback in metal forming with a fluid cell press through establishing a computational formulation to determine bend angle and compensated die radius based on factors of geometry of the part being formed, material properties of the sheet material and the forming process, and computing additional iterations of springback until a specific tolerance between the formed part angle and the desired part angle are reached.

Abstract: The invention relates to a method for producing bent spring rails from an endless spring band. The method is characterized by the following steps: continuous bending of a section of spring band; cutting the bent section of spring band into a spring rail; discontinuous reverse bending to reduce the internal stresses of the bent, cut-to-length spring rail by subjecting the spring rail to at least one reverse bending force and/or heat-treating the cut-to-length spring rails, the heat treatment being a low-temperature treatment in this case, preferably at a temperature of less than 200 *C.

Abstract: A hollow rack shaft is manufactured through a first step, a second step and a third step. At the first step, the plate-like workpiece of substantial rectangular shape is press formed into a gutter-like shape. The first die set used at this step is provided with slant die surfaces for canceling elastic recovering generated at the workpiece when the workpiece is removed from the first die set. At the second step, a row of rack teeth is press-formed on the flat bottom portion of the workpiece formed in the first step. The die set used at the second step is provided with a recess for releasing surplus workpiece material within the die clearance at a stroke end of the pressworking. At the third step, each of a pair of legs of the workpiece is bent in a semi-circular shape so as to be butted to each other. At this time, a mandrel is inserted between the legs of the workpiece.

Abstract: In bending a workpiece, a position of the workpiece relatively pressed down by a punch is directly detected by a plurality of position detectors provided in a V-groove of a die, and a bending speed calculation section obtains a bending speed from a change in this position. If bending speeds at position of the respective position detectors differ, a uniform speed arithmetic operation section calculates a bending speed to make the bending speeds at the positions of all of the position detectors, and a driving shaft instruction section controls driving shafts to bend the workpiece at the uniform bending speed.

Abstract: A bending apparatus reciprocates at least one of an upper table to which a punch is mounted and a lower table to which a corresponding plurality of adjacent divided dies are mounted. At least one bending angle detector is provided between the dies to detect a bending angle of the workpiece. A main body inserts the bending angle detector into a gap between the dies and withdraws the bending angle detector from the gap between the dies. A lift is biased upward by a first elastic body and is configured to be pressed downward by the workpiece at approximately a center of a groove portion of the dies. The lift includes a first engagement member. A rotor support is biased upward by two second elastic bodies having smaller biasing forces than the first elastic body. The rotor support includes second engagement members. Two rotors are provided on opposite sides of the groove portion at an upper portion of the rotor support. The two rotors include workpiece contacts that contact the workpiece.

Abstract: A bending method includes determining a provisional bending stroke value that resulted in a predetermined angle during test bending. The bending method also includes calculating a stroke value correction amount for correcting the provisional bending stroke value, based on the number of times a test piece was contacted to obtain the predetermined angle during test bending. The stroke value correction amount is added to the provisional stroke value to obtain a corrected stroke value, so as to obtain the predetermined angle during operational bending using the corrected stroke value.

Abstract: A method of operating a bending press, in particular an edging press, and a bending press for carrying out this method. For each drive of a drive arrangement, the actual pressing force is detected for the displaceable press beam during a bending process for the workpiece and a relative position of the pressing tool or tools by reference to the longitudinal extension of the press beams is determined on the basis of a force ratio. Different displacement paths of the drives and the displaceable press beam at the respective force-application point of the drive are then determined in an evaluation and/or computer unit, which is provided with a data memory for production and machine data, and corresponding control signals for the drive system are generated in the control unit and actuator elements of the drives are displaced by the displacement paths determined for each drive.

Abstract: Methods are provided for forming a hollow rack shaft from a workpiece comprising a rectangular plate. The workpiece is first bent into a gutter-like shape using a first die set. Rack teeth are then press-formed in a portion of the gutter-like shape using a second die set. The legs, or sides, of the workpiece are then bent around a mandrel into a semi-circular shape so as to butt against each other. Preferably, the die sets and mandrel may be adapted to improve the resulting hollow rack shaft.

Abstract: A system manufactures a product by bending a sheet material includes a three-dimensional stereoscopic diagram creator that creates a three-dimensional stereoscopic diagram, including a desired bending angle and a desired flange width, based on graphic information of a product. A displayer displays a bending angle value in the vicinity of a bending angle, and/or a dimension value in the vicinity of a flange, in the created three-dimensional stereoscopic diagram. A test piece displayer displays a test piece of a material proposed for use in the product and displays the bending angle value(s) in the vicinity of the bending angle(s), and/or the dimension value(s) in the vicinity of the flange(s), of the test piece. A measuring device measures the bending angle value(s) and the dimension value(s) for the test piece bent by the bending machine.

Abstract: A bending method is provided for bending two sides of a workpiece to form flanges. The bending method includes measuring a bent flange to obtain a flange dimension. The bending method also includes setting a back gauge value for processing another flange, based on a measured dimension of the workpiece. The other flange is bent using the set back gauge value.

Abstract: An angle detecting head provided with an emitter and a pair of receivers is rocked, and a bent surface of a workpiece bent by a punch and a die of a bending machine is irradiated with a measurement light from the emitter, a reflected light is received by the pair of receivers, and a bending angle of the workpiece is obtained from a peak value of the light received by the respective receivers. The angle detecting head is movable parallel to the die, is movable in a direction close to and away from the workpiece, and is movable in a direction in which the die is raised/lowered. The angle detecting head is positioned in an optimum angle measurement position of the workpiece and the bending angle is measured.

Abstract: A three-dimensional stereoscopic diagram creator creates a three-dimensional stereoscopic diagram including a desired bending angle based on graphic information of a product. A major dimension displayer displays a major dimension, tolerance and the like with respect to the three-dimensional stereoscopic diagram. On the other hand, a test piece displayer displays a test piece of the same material proposed for use as the material used for producing the product. The test piece displayer carries out trial bending on the test piece. A bending angle after a bending load is removed is measured by a bending angle measuring device. A spring back amount setter calculates a spring back amount from a difference in bending angle between before and after the load is removed. A stroke calculator calculates a stroke value relative to the desired bending angle considering the obtained spring back amount. Actual bending is performed on a product piece using the calculated stroke value.

Abstract: A numerical control device for a bending machine includes a keyboard, a memory and a processor. The memory stores one or more groups of data, each containing bending conditions, a bend angle and at least one penetration depth. The memory further stores program instructions for searching whether data input with the keyboard is stored in the memory, in a same group of data, and that sends a signal to the bending machine so that the bending machine peforms bending according to the penetration depth included in the group of data. The processor that executes said program instructions.

Abstract: A method of making a face mask including the steps of providing a plurality of lengths of Grade 2, commercially pure titanium wire, having a diameter of from about 0.21 to about 0.24 inches; forming each length at room temperature to a desired bend angle by bending the member at room temperature using rotary bending apparatus to a first bend angle that is from about 1.25 to about 1.35 times greater than the desired bend angle; and welding each of the thus formed lengths to at least one other of the lengths in an ambient, oxygen containing environment.

Abstract: For the manufacture of a ring part out of a flat sheet-metal part to form a lid for a lid of a can. A hot-sealable coating is provided on one side of the sheet-metal part which is then shaped into a cylindrical tube with the coating being on the inside. The axially extending edges of the tube are joined together to form a butt-joint and the inside surface thereof pressed against a cooling plate. A butt-joint welding seam is then created by means of a laser jet. The tube is separated into equal length tube sections and each is conically enlarged at one end. The other end of each tube section is bent radially inwardly to form a bearing surface for a tear-off foil. By flanging the conically enlarged end, an annular flange is created to receive a body of a can.

Abstract: The invention provides a method and an apparatus for determining the bending angle of a work piece to be bent by means of a bending apparatus comprising a punch member and a die member cooperating with the punch member. The die member is provided with at least two channels through which pressurized air is blown towards a leg of the bent work piece. For measuring the pressure in each of the channels, a plurality of pressure sensing devices is provided and connected to a common control and analyzing assembly. On the basis of the pressure values measured by the pressure sensing devices and with the aid of formulae, tables, three dimensional diagrams or with the aid of a neuronal network, the control and analyzing assembly calculates the bending angle.

Abstract: The numeral control device for a bending machine comprises means for inputting, as input data, a desired bend angle and bending conditions or criteria, means for storing groups of data, each containing bending conditions, a bend angle and a penetration depth, and means for searching whether the input data is stored in the memory means, in the same group of data. Moreover, means are provided for transmitting a signal representative of a penetration depth included in the group of data stored in the memory means, or for transmitting a signal for controlling the bending machine according to this penetration depth.

Abstract: A press-bending machine to bend metal sheets, having improved features in the respective press-bending with measuring and control system operating on at least four points of the bending angle, of the type in which the press-bending machine has: an upper vertically reciprocal elongated bending punch; a lower static elongated bending matrix with at least a longitudinal bending groove; feeler means to measure the respective bending movement of the metal sheet in bending inside said bending groove, to control by data process logic unit the bending parameters of bending process in said bending machine, said feeler means operating with at least four bending detection points, characterized in that all said detecting points are conceived in such a way to be divided in two sets of bend detecting points, one to one side and one to the other side and in a symmetrical way divided in number and position respective to the vertical plane passing along the respective sheet bending line corresponding with the bending corner o

Abstract: A pipe bending system employing a feedback and control system that provides continuous data to a programmed processor. The processor is programmed to automatically carry out an incremental bending cycle in which the pipe is clamped by a predefined pressure by the pin-up shoe, a stiffback is moved upwardly to a predefined position to achieve a desired angular bend in the pipe, the stiffback is returned to its fill back position, as is the pin-up shoe, whereupon the pipe is axially moved a predefined distance to proceed with the subsequent incremental bend.

Abstract: An apparatus and method are provided for integrating an intelligent manufacturing system with an expert sheet metal planning and bending system. The intelligent manufacturing system manages and distributes part design and manufacturing information throughout the locations of a production facility. The expert planning system includes a plurality of expert modules for proposing a bending plan, including bend sequence and tooling selections, and robot motion planning and repositioning. Through the various features and aspects of the present invention, an operator can selectively modify and adapt these integrated systems for particular bend applications, including robot-based and human assisted bending operations.

Abstract: A bend angle correction method directed to carrying out simple and accurate penetration of a movable die into a fixed die to produce a uniform angle throughout the length of a workpiece, being unaffected by material variations. When bending a sheet-like workpiece to a desired angle by the cooperative movement of a movable punch driven by three or more drive shafts and a fixed die disposed in an opposing relationship with the movable die, the bend angle of the workpiece is measured during bending operation and the difference between the measured bend angle and a target angle is obtained, at at least three points which are the ends and center of the workpiece. Based on the differences, correction amounts for the penetration of the movable die are obtained on a shaft-load imposed point basis.

Abstract: A major object of the present invention is to compensate for variations in springback angle resulting from variations in material properties from one lot to the next, for the realization of high angle accuracy bending. Based on the difference between a workpiece actual bend angle detected during bending and an estimated bend angle of a workpiece W at an arbitrary penetration point of an upper die 5, a correction value for prestored data relating to a springback behavior under a processing condition is obtained. Based on the correction value, a final penetration point of the upper die 5 is obtained.

Abstract: For the purpose of making it possible to estimate the spring back angle and/or final driving position of the driving die with good accuracy even if there are some variations from lot to lot in the material characteristics values, and thereby achieve bending with extremely high angle accuracy, the actual bending angle is directed at no less than two provisional driving positions of the driving die during the bending of a workpiece. Based on the relationship of the amount of change in the driving amount to the amount of change in the actual bending angle relating to those provisional driving positions, a determination is made of the relationship of the spring back angle to the target bending angle of the workpiece for the respective working conditions of the bending concerned which are stored in advance. From this relationship, a determination is made for the final driving position of the driving die, and the driving die is driven to that determined final driving position.

Abstract: Apparatus and method for the bending of rigid workpieces, particularly tubes, such as those of use in automotive exhaust systems, heat exchangers and aircraft hydraulic systems.

Abstract: In a press bending arrangement for an aluminum profile, especially for manufacturing the equator profile for an LNG-tank, the press is connected to control and measuring devices in such a manner, that the reflection of the workpiece is taken into account both in bending the profile and in determining the bending control based on measurements being made.

Abstract: As part of a process for bending workpieces (14), when the workpiece (14) is released from the upper die (8) and/or the lower die (10), the actual size of the bending angle (.beta.) is continually determined; from the actual size of the bending angle (.beta.) found, the change in it is determined and, as soon as the change in the actual size of the bending angle (.beta.) assumes a predetermined value, the actual size of the then existing bending angle (.beta.) is compared with the desired size.On a tooling machine for carrying out the method described, there are scanning elements (17,18) and a device (24) for determining the actual size of the bending angle (.beta.) that are parts of a device (19) for determining the change in the actual size of the bending angle (.beta.). The device (24) for determining the actual size of the bending angle (.beta.) is connected to a comparison device (32) for comparing the actual size of the bending angle (.beta.) to the desired size.

Abstract: For starting bending of a workpiece, a provisional drive end for a ram is computed from information such as processing conditions for the workpiece input through a processing (condition input section and the relationship between the target bending angle for the workpiece and the springback angle of the workpiece stored in a springback data section. The ram is driven to the provisional drive end and then the bending angle of the workpiece is measured thereat by an angle measuring unit. Thereafter, a final drive end for the ram is obtained from (i) the measured bending angle, (ii) the relationship between the bending angle of the workpiece and the amount of driving the ram stored in a bending angle vs. driving amount data section, and (iii) the relationship between the target bending angle for the workpiece and the springback angle of the workpiece stored in a springback data section. The ram is driven to the final drive end thus obtained to complete the bending operation.

Abstract: Both a method and apparatus are disclosed for forming a bend in an elongated member, such as a tube, at a predetermined target angle. The elongated member is first bent to an angle equal to the target angle plus a predetermined increment. The elongated member is then returned to the target angle and a value representative of the force necessary to maintain the elongated member at the target angle is inputted into a central processor. This inputted value is then compared with a threshold value and, in the event that the inputted value exceeds the threshold value, the predetermined increment is incremented and the above steps are repeated until the inputted value is less than the threshold value. An apparatus for performing the method of the present invention is also disclosed.

Abstract: A method and device for folding a metal sheet to a well-defined angle, in which the sheet is deformed in the recess of a die through a punch being moved above the recess and pressing on the sheet, towards the die, until it reaches a well-defined end position. The movement of the punch is regulated as a function of the folding force and of the folding angle. The punch is moved in the direction of the die until it is in an end position Ya corresponding to: Ya=Yt-dYw-dYr in which Yt is a calculated position, dYw is determined through extrapolation of the course of the folding angle as a function of the position of the punch, and dYr is the correction of the position of the punch which is necessary to compensate for the spring-back of the sheet.

Abstract: A tube bending system for bending all tubes in a preset manner effectively from the beginning of works by detecting a degree of bending of a tube which varies during a bending process in high precision by a displacement sensor and by accurately comparing the detected value of the degree of bending of the tube detected by the displacement sensor with a control value written in advance in a program in a memory. The displacement sensor is disposed so as to be able to detect the position of the tube to be bent on the side of a reaction receiving section between a gripper and the reaction receiving section. The displacement sensor is composed of a detecting section and a transducing section.

Abstract: A method of bending extruded shapes of the present invention controls a bending radius and a bending angle in accordance with a moving distance of a movable bending die. In the bending process, hardness of an extruded shape to be processed is measured and converted into proof stress, and the bending condition for compensating the springback is determined. A correction coefficient C showing a ratio of a practical value of the moving distance and a theoretical value of the moving distance in a case of no spring-back occurring is defined by a function of Young's modulus E, geometrical coefficient Z, bending radius R and proof stress .sigma..sub.0.2 for the extruded shape to be processed.

Abstract: A system for adjusting the gram load, static attitude roll and radius geometry of a suspension with a high degree of accuracy and repeatability includes a clamp, load-engaging member, actuator, laser and control system. The mounting region of the suspension to be adjusted is releasably received and clamped by a clamp. A load beam of the suspension is engaged and supported at adjust positions with respect to the clamp by the load beam-engaging member. The load beam-engaging member is driven and positioned by the actuator. IR light from the laser is directed to the spring region of the suspension by optical fibers. The control system includes a pre-adjust input terminal, memory and a controller. Information representatives of a measured pre-adjust fly height gram load, static attitude roll and radius geometry values of the suspension are received at the pre-adjust input terminal.

Abstract: A device for measuring an angle in a workpiece piece which includes a base; a pair of feelers which are movable relative to the base and each of which has an active surface for contacting a respective portion of the workpiece piece during the measurement; a thrust mechanism for bringing the active surfaces of said feelers into contact with the respective portions of the workpiece piece being measured; and a sensor mechanism for detecting the positions of the feelers relative to the base.

Abstract: A method of permanently bending a first part of a subject body having non-linear elastic properties about a bending line to a desired angle relative to a second part of the body in which a first set of data is produced from similar bodies of the amount of permanent bending obtained as a function of different amounts of angular displacement of the first part, the first part of a subject body is permanently bent to a first angle different from said desired angle by angularly displacing the subject body's first part by an amount determined by the first set of data and thereafter the first part of the subject body is further angularly displaced from the first angle to permanently bend its first part to the desired angle.

Abstract: A method is disclosed for developing the contour of tools employed for forming members exhibiting complex shapes. The members may be precipitation, heat treatable, metals or metal alloys which are age formed, although they be of any material which exhibits a relationship between a strain applied by a forming tool, or otherwise, and a resulting strain after release of the applied strain. The resulting member may be formed to the desired contour as a result of exposure to an elevated temperature but the member may also be cold formed. The invention is particularly concerned with a methodology for simplifying the analysis of integrally stiffened structures of complex shape. The method of the invention assures proper results on the first occasion the tool is used, thereby resulting in considerable savings of labor and material.

Abstract: A method and equipment for bending a work to the extent of a target bending angle, including a first process of bending to bend a work with a ram driven by a two-shaft system having a pair of right and left drive mechanisms to the extent of the quantity of motion for each shaft corresponding to the target bending angle, a measurement process to measure the bending angles at both ends of the work bent in the first process of bending, a correction process to correct the quantity of motion for each shaft according to each error between the target bending angle and the respective bending angles at both ends of the work measured in the measurement process, and a second process of bending to bend the work with the ram driven by the two-shaft system in which each shaft is actuated by each drive mechanism to the extent of the quantity of motion for each shaft corrected by the correction process, all of the above processes being performed in series.

Abstract: A remotely positionable bending apparatus includes a support platform with a mandrel mounted to a front surface thereof and a bending arm pivotally connected between the mandrel and support platform. The outer end of the bending arm rotates around the upper end of the mandrel to bend a rod into a generally inverted U-shape. A clamping apparatus is operably mounted on the platform adjacent the mandrel and includes an actuator which is operated by movement of the bending arm to clamp and release a detector rod in a retained position against the mandrel. Preferably, the actuator includes a shaft which is placed under a biasing force to urge the shaft into a clamped position, with a pivotable lever connected thereto actuatable to overcome the biasing force and release a detector rod from the clamped position. The actuator lever is located in the pivotal path of the bending arm, such that movement of the bending arm to a retracted position disengages the clamping apparatus from the detector rod.