Machine and process for straightening pieces of small cross section and great length

Abstract: A machine (10) for straightening pieces of small cross section and great length, comprising supporting means of a piece (11) to be straightened, associated with a system of applying the force and a system for measuring and controlling the process, also providing a system for feeding and advancing said piece (11), where the system feeding the pieces (11) to be straightened provides two clamps (12, 13) acting on the piece (11) to be straightened, so as to move it to the various operating positions. It is also described a process of straightening pieces of small cross section and great length, performed by using the mentioned machine.

Description: The object of this invention is a machine as well as a process performed by using said machine, destined for straightening pieces of small cross section and great length. Typical examples of pieces of small cross section and great length are profiles of an l, C, I or T shape and of a square, rectangular or any other form of a size up to 100 mm and length up to 10 meters. The profiles have an initial deformation of a flexing or twisting type derived from the fabricating process, such as for instance produced by the internal tensions, which are induced by the heat treating process of quenching, which must be eliminated before being rectified. Two specific machines, one for each type of deformation, are provided for this purpose. The straightening is carried out by applying a flexing or twisting moment to the piece, so as to produce a plastic deformation and the ensuing tensions sufficient to compensate those present in the piece. The required straightening tolerances are typically in the order of 0.1 mm/meter, so as to minimize the material to be removed in the subsequent rectifying operation. The process is carried out by alternating measuring phases with straightening phases commensurate with the measured errors. The machine utilized to this date comprises a mechanical structure constituted by a mobile bench and a cross beam, an error measuring and controlling system and some appropriate equipment. The equipment consists of a series of supports and punches in a number adequate for the required type of deformations of the piece to be straightened, mounted respectively on the base and on the cross beam and appropriately installed based on the measured deformations, so as to produce, by the motion of the cross beam, the deformations required by the straightening process. The pieces are first straightened on one side and then rotated to the other. In EP-A-0 074 760, a bending and straightening machine is provided for long material to be straightened and has straightening abutments which are arranged at a distance from one another in the longitudinal direction of the material to be straightened and between which are arranged straightening rams. The principal drawbacks of this technology are the high cost of the machine and its long straightening time. The machine described by this invention has been developed to overcome these limitations. The purpose of this invention is therefore to implement a machine and a straightening process capable of solving the mentioned problems. Another purpose of the invention is to produce a machine for a simple and inexpensive straightening process, capable of operating in a fast, effective and precise manner. These and other purposes are achieved by a machine for straightening pieces of small cross section and great length, according to claim 1, which is being referred to for brevity. The further object of the invention is a process for straightening pieces of small cross section and great length. Moreover, additional characteristics of this invention are described in the subsequent claims. Further purposes and advantages of this invention will become clear from the description and attached drawings to follow, supplied as a purely explanatory and nonlimiting example, in which: Figure 1 shows a simplified view of a straightening machine according to this invention, in a first operating position, Figure 2 shows a simplified view of the straightening machine shown in Figure 1, in a second operating position, Figure 3 shows a simplified view of the straightening machine of Figure 1, in a third operating position, and Figure 4 shows a simplified plan view of the straightening machine according to the invention, during a straightening phase. The machine for straightening pieces of small cross section and great length according to this invention is indicated as a whole by the reference number 10 in the attached figures. The machine 10 consists essentially of a feeding and advancing system for the piece, a system for applying the force, and a system for measuring and controlling the process. More in detail and with reference to the mentioned figures, the machine 10 offers a feeding system for the pieces 11 to be straightened, constituted by a pair of mobile clamps 12 and 13. A supporting roller 14, 15 and a probe 17, 18 is provided next to each clamp, so as to operate as a measuring device, in combination with a third probe 22 set up along the axis of the punch. The clamps 12, 13, are always moving symmetrically in relation with the axis of the machine, thanks to a servomotor and a toothed belt 16, on which the clamps 12, 13 are respectively engaged with the parts 12', 13' and the respective probes 17, 18 move together with said servomotor and said belt 16. Each of the supports 14, 15 carries an optical sensor unit 20, 21 which forms a sensing barrier and is designed to detect the presence of the piece 11 to be straightened. While straightening the piece 11, the same is flexed by a punch 19, to the point of producing an effort adequate for a permanent deformation of part of the material. The operation of the machine for straightening pieces of a small cross section is illustrated in the part following this description. The piece 11 to be straightened is initially positioned with one of its extremities inside the sensor barrier, as shown in Figure 1. The supports are slightly shifted toward the outside, so that the extremity of the piece 11 is positioned halfway across the support 12. The piece 11 is moved to such a position as to reach the second clamp 13, as shown for exampie in Figure 2; this position is subsequently recorded as a zero position, by using the optical sensor unit 18 of the second clamp 13. At this point the piece 11 is held in position by the two clamps 12, 13, while the first extremity of the piece 11 is kept at a predetermined distance from the optical sensor unit. This allows performing a first straightening step for the first section of the piece 11, which is subsequently moved on by about half a section. This motion is achieved as follows: opening of the clamp 13, shifting of the clamps 12, 13 toward the center of the machine 10, closing of the clamp 13, opening of the clamp 12, shifting of the clamps 12, 13 in an opposite direction, and closing of the clamp 12. It is now possible to perform a second straightening phase for the second section of the piece 11, as shown in Figure 3. The procedure described above may be repeated as often as required, until reaching the final section to be straightened. If any piece requires two separate straightening planes, the piece is first straightened along one plane, for all the sections involved and by the process described above, and then rotated by 90° so as to be further straightened in all the sections along the second straightening plane. Further characteristics of the straightening process according to an embodiment of the invention bear above all on the fact that the length of the individual steps is programmable. Moreover, the stroke length of the punch is commensurate with the error measured. The process also takes care of measuring the deformation of the profile section under work, the calculation of the stroke for the punch, the application of the deforming force, a new measurement of the deformation of the piece, and the eventual repetition of the cycle until reaching the desired tolerances. The punch may apply the deforming force in either a pushing or pulling mode, depending on the curvature of the piece. In order to minimize the overall deformation of the piece, the straightening tolerances for some adjacent sections provide for some residual curvatures in opposite directions. In practice, the machine according to the invention makes it possible to achieve the stepwise straightening of the piece, while preventing a simultaneous straightening along the entire length of the piece 11. This above description of the machine, its operation and advantages clarifies the characteristics of the machine and of the process for straightening pieces of small cross section and great length as described in this invention. It is finally evident that numerous variants may be applied to the machine and its process as an object of this invention, without thereby abandoning the innovative principles of this invention as defined in the appended claims. In the practical implementation of the invention, the materials, the shapes and sizes of the details illustrated may be of any kind, depending on the requirements, and the same may easily be replaced with others of a technically equivalent type.

Claims: A machine (10) for the straightening of pieces (11) of small section and great length, of a type comprising supporting means of a piece to be straightened, associated with a system for applying the force comprising a punch (19) and a system for measuring and controlling the process, further comprising a system of feeding and advancing said piece (11), characterized in that the mentioned feeding system for the pieces (11) to be straightened provides for two mobile clamps (12, 13) operating on said piece (11) to be straightened, so as to move it to the following processing positions, each of the mentioned clamps (12, 13) being movable symmetrically with respect to an axis of the machine and in that said punch (19) is located between the two mobile clamps (12, 13), and is capable of subjecting said piece (11) to a flexing motion either in a pushing or in a pulling mode. A machine (10) according to claim 1, characterized in that next to each of the mentioned clamps (12, 13) is associated with a supporting roller (14, 15) and a probe (17, 18), acting as a measuring device in combination with a third probe (22). A machine (10) according to the claims 1 or 2, characterized in that each of the mentioned clamps (12, 13) moves symmetrically with respect to an axis of the machine by using a servomotor and a toothed belt (16). A machine (10) according to claim 2 or 3, characterized in that each of the probes (14, 15) moves in the same manner as the mentioned clamps (12, 13). A machine (10) according to one of the preceding claims, characterized in that each of the mentioned clamps (12, 13) carries an optical sensor unit (17, 18), which serves to detect the presence of the piece (11) to be straightened. A machine (10) according to one of the preceding claims, characterized in that it provides for a system for measuring the deformation of the piece, for commesurating the stroke lenght of the punch (19), capable of subjecting said piece (11) to a flexing motion, with the error measured, up to the point of producing a strain sufficient to permanently deform part of the material. A process for straightening pieces of small cross section and great length, comprising a first phase in which the piece (11) to be straightened is moved from an initial position, by using first and second mobile clamp (12, 13), up to a reference position in which said piece (11) reaches the second clamp (13) where the mentioned piece (11) is held in position by the mentioned clamps (12, 13) so as to perform a first straightening phase for a first section of the piece (11) by means of a system for applying the force comprising a punch (19), located between the two mobile clamps (12, 13), and capable of subjecting said piece (11) to a flexing motion either in a pushing or in a pulling mode, a phase of advancing the mentioned piece by about half a section in order to perform a second straightening phase of a second section of the piece (11), whereby the mentioned straightening phases of a section and advancing the mentioned piece (11) are repeated a necessary number of times, until all the sections of the piece (11) are straightened, whereby the advancing motion of the mentioned piece (11) is performed by opening of a first clamp (13), shifting of both of the clamps (12, 13) toward the center of said machine (10), closing of the mentioned first clamp (13), opening of a second clamp (12), shifting of the mentioned clamps (12, 13) in an inverse direction and closing of the mentioned second clamp (12). A process for straightening pieces according to claim 7, characterized in that the piece (11), whenever any pieces provide for two different straightening planes, is first straightened along a first plane in all the sections to be straightened, and then rotated by 90 DEG in order to also be straightened along all the sections of the second straightening plane. A process for straightening pieces according to claim 7, characterized in that the length of the individual steps is programmable. A process for straightening pieces according to claim 7, characterized in that the stroke of the punch is commensurate with the error measured. A process for straightening pieces according to claim 7, characterized in that it provides for measuring the deformation of the profile section being processed, calculating the stroke of the punch, applying the deforming force, remeasuring the deformation of the piece, and an eventual repetition of the cycle, until achieving the desired tolerances. A process for straightening pieces according to claim 11, characterized in that the punch can apply the deforming force in either a pushing or a pulling mode, depending on the curvature of the piece. A process for straightening pieces according to claim 12, characterized in that for the purpose of minimizing the overall deformation of the piece the straightening tolerances of adjacent sections provide for residual curvatures in opposing directions.

Inventors: GALDABINI LUIGI, GALDABINI, LUIGI
Applicants: CESARE GALDABINI S P A, CESARE GALDABINI S.P.A.
Application year: 2001
Main classification: B21D3
IPC codes: B21D3