SU1178522A1 - Method of straightening blanks - Google Patents

Abstract

1. A METHOD FOR CORRECTION OF BLINDS, including eliminating the curvature of the straightened part of the workpiece by bending by applying two oppositely directed pairs of forces to the boundary sections of the section, characterized in that, in order to improve the accuracy and accuracy, before the elimination of the curvature, it is distributed evenly the length of the work piece by local bending of the middle part of the stretched part with two oppositely directed forces applied to the boundary sections of this chastka. 2. Method POP.1, characterized in that before eliminating the curvature, the difference between the actual and calculated deflections in the middle of the straightened section is determined, and in the process of uniform distribution of the curvature along the length of the workpiece section, the difference of the deflections is reduced to zero, after which the opposite sign is created these deflections, increasing it from zero to the value determined by the outcome (The difference between the mentioned deflections and the elastic properties of the workpiece, and the calculated deflection is determined from the ratio where -t to Y is etstvenno distance of kj and the angle between the boundary sections 00 ate E straightening emogo blank portion.

Description

The invention relates to the processing of metals by pressure, in particular to the technology of straightening of sectional and sheet metal, pipes and machine parts of elongated shape, and can be used in metallurgy, mechanical engineering and other public sectors to eliminate the curvature of workpieces on correct machines with turning in one plane with clamping heads. There is a known method for dressing editing, which includes eliminating the curvature of the straightened part of the workpiece by bending by applying two oppositely directed force pairs l to the boundary sections. The purpose of the invention is to increase the productivity and accuracy of straightening blanks with symmetrical curvature. Figure 1 shows a scheme for determining the design deflection; in Fig.2 the position of the workpiece with a negative difference in deflections before the start of the first operation; in FIG. 3, the positions of said blank in the loaded state when performing the first operation; Fig. A shows the position of the said preform after the end of the first operation; in FIG. 3, a curvature of the bending moments corresponds to the loading scheme shown in FIG. 3; figure 6 - the position of the workpiece with a positive difference in deflection before the first operation; in Fig. 7, the position of said preform in a loaded state when performing the first operation; Fig. 8 shows the position of the aforementioned workpiece after the completion of the first operation, Fig. 9 is a plot of bending moments, corresponding to the loading scheme shown in Fig. 7; figure 10 - the position of the workpiece before the start of the second ration; Fig. 11 illustrates the position of the aforementioned preform in the loaded state when performing the second operation; Fig. 12 shows the position of the said blank after the end of the second fraction; Fig. 13 is a plot of bending moments, corresponding to the loading scheme shown in Fig. 11. The method is carried out as follows. Before performing the basic operation of eliminating the curvature, an auxiliary operation of its redistribution is performed. The elimination of curvature is carried out by loading the workpiece with two equal pairs of forces of a mutually opposite direction applied to the boundary sections of the straightened section in the plane of its curvature, and the redistribution of curvature is carried out by loading the workpiece with two equal forces of a mutually opposite direction also applied to the mentioned sections in the plane the curvature of the straightened area. In order to determine the conditions required for deciding on the modification of the curvature redistribution operation, it is necessary to measure оС angles and deviations of the boundary cross-sections of the plot being stretched from the zero position (from the axis of the nd1 –Jn axis) 0 and Oa of the mentioned boundary sections (Fig. 1). The angles oC and / b are the main indicators of the curvature of the straightened area. With the inequality of angles SK. and f, the section is bent by applying a pair of forces to one of the boundary sections until the equality of these angles is achieved after unloading (the indicated operation of eliminating the asymmetry of the curvature of the straightened section (not described, as it goes beyond the claimed technical solution). calculate the calculated deflection fp, which is understood to mean the deflection of an imaginary section, the parameters of ° C, p and t of which are equal to the corresponding parameters of the actual section, and the longitudinal axis has the shape of an arc of a circle. The initial curvature of such an imaginary section can be expressed by the ideal straightness of a pure bend by applying equal pairs of forces to its boundary sections. The boundary and average transverse sections of the real section, the initial position of which completely corresponds to the initial position of the same sections of the imaginary section, after editing by the mentioned pairs forces occupy a position that also corresponds to the ideal position of the boundary and average sections of an imaginary segment (, OST 0,). At the same time, the remaining cross sections are thanks to the complete 3

The workpiece also occupies a position close to the ideal, and the degree of approximation of the actual position of the sections to the ideal remains large enough even for long sections (for sections d /) j420-30, where t is the section length, h is the thickness of the workpiece in the bend plane).

The calculated deflection fp is defined as the height AB of a flat segment formed by the chord OjOa and an arc of a circle of radius R with the center of curvature at the point O (Fig. 1). The segment chord is equal to the distance t, and the central angle of the arc drawn by the chord is equal to the angle Y between the boundary sections of the segment.

From triangle 00iB

R (0,5tf - -CK-fp)

From here

,

Here

I b, 5t / siM 0.5 U,

where TG is the angle of curvature of the area (the angle between its boundary sections.) Y. After substitution we have

fp S-f

After determining the calculated deflection from the indicated expression, it is equalized with the actual deflection in the middle of the straightened section. If the difference between these deflections is zero or less than the allowable, there is no need to perform a redistribution of curvature, and the area is right bend by turning the boundary sections at equal angles.

If the difference between the actual and calculated deflections exceeds the allowable one, before eliminating the curvature, redistribute it by loading the workpiece with two equal forces until equality between the actual and calculated residual deflections is achieved.

Said first operation of the proposed method is carried out either

785224

by combining the boundary sections of the straightened section (Figures 2-5), or by their dilution (Figures 6-9).

If, after clamping the workpiece 1 in 5 jaws of the clamping heads 2, which can be rotated in the plane of the drawing relative to the points Of i.Oa, it turns out that cCx Jbiicx, and fjicx {R.i. (the initial difference of the deflections is 10 negative), the first operation is necessary by reducing the boundary sections (Fig. 2). For this, R boundary sections are applied along the axis of the straightening m-np to compressive forces T of the opposite direction (Fig. 3). As a result of loading the workpiece with a moment Tf, where 1N deflection under loading, the deflection angles increase and become equal to cX. (T, 20 Both deflections also increase, but the actual deflection increases faster than the calculated deflection. As a result, the difference between these deflections decreases first to zero, and then again, 25 begins to increase, but already in the range of values of the opposite sign. The workpiece is unloaded from the action of the forces T when the opposite in sign is reached by the difference {- - {rn of the 3Q height, which should be the greater, the larger the initial visibility of the deflections ijfvn - fp.MM and the greater the elastic limit of the workpiece material.

The specific value of the inverse of the difference between the actual and calculated deflections is determined by the operator on the basis of experience (as when editing the press) or 0 is automatically determined (technical solutions underlying the operation of the automatic control system are not disclosed). After unloading the workpiece from the action of the force 5., the straightened area as a result of loading is somewhat straightened, the deviation angles of the boundary sections decrease and become equal-osg, osg.

Q Both deflections are also reduced, but the actual deflection decreases faster than the calculated deflection and at the end of the load, the equality fost fp takes place. OST (Fig. 4).

When loading, the distance between the boundary sections, in the initial position, equal to ± nfcc decreases to bn, and when unloading it increases again to equ. After the first operation, the vertical section approaches the arc of a circle by increasing the initial curvature in the middle of the section where the actual bending moments exceed the maximum elastic bending moment W: W, where bGt is the yield strength of the workpiece material, and V is the resistance point cross section (Fig.5). If, after clamping the workpiece in the lips, it appears that /. , and fHcx fp.HC (Fig. 6), the first operation is carried out by diluting the boundary sections of the straightened section by applying to it a stretching force T of a mutually opposite direction (Fig. 7) until equality totT fr. OST (Fig.8). With this loading scheme, bending moments appear in the cross sections of the section, bringing the section closer to the shape of the circular arc by reducing the curvature in the middle zone of the section, where from the dying moments, the values of 0rW are exceeded (Fig. 9). In the first operation, the specific value of the force T or the amount of movement of the left clamping head in the direction of the t-axis editing axis is used by the operator on the basis of the scientific research institute for the results of visual comparison of the shape of the straightened section with the circular arc shape or is determined automatically using the value of the calculated calculated value deflection. Both with manual and automatic process control, the magnitude of the created difference between the actual and calculated deflections must be inverse to the sign of the initial difference of these deflections and somewhat exceed the original difference in absolute value. The second operation of the proposed method, which is the elimination of the curvature of the straightened section, is carried out by pure bending by turning the boundary sections at equal angles (Figures 10-13). The angles of the initial deviation of the LIS of the CLAIM and the initial deflections) Grisk before performing the second operation (Fig. 10) are the angles of Compos, JioCT and the deflections focTf fp.ocT obtained after performing the first operation (Figures 4 and 8). Due to the fact that the shape of the straightened section is close to the arc of a circle, the section is bent by applying equal pairs of forces Ml and -Mr of mutually opposite direction to its boundary sections, resulting in a net bending of the workpiece with a change in the sign of the angles and deflections, but with preservation of equalities n / & n and 1n {ph (Fig. 11). With a proper choice of the magnitude of the bending moment, the indicators of the residual curvature of the section after its unloading take on values that do not go beyond the limits of permissible values of OST. and, fow The second operation can also be controlled manually or automatically. Example. A workpiece having a rectangular cross section with sides of L 40 mm, L 20 mm and made of steel with a tensile strength of BT 25 kgf / mm was ruled in a plane of lesser rigidity. After clamping the workpiece in the jaws, the initial parameters of the straightened section were: 1 45 458.1 mm, cf. , 9,, 3 mm. The calculated deflection of the elongated area in the initial position was determined from the expression f tttcf. . ofntu .f 458.1 R.ish - -Ч4 2 t (l13.9h (13.9) 2 ,,, due to the fact that the initial difference in deflection / f nsx / - out / The first operation of the method was carried out by combining boundary sections by moving the left head with a force Vy iicx, where fa is the relative bending moment, / b is the cross section resistance moment. The larger the deflection difference and the shorter the fucx distance, the greater should be the value of W. Considering the workpiece material to be non-reinforcing, whether m 1.1. Then "1.1 25 4020g -„ .-, T - r., 9 10 kgf 2.9 ts. 7 After the boundary sections are reduced by the forces T, the parameters of the straightened y the chunk was: t 446.2 mm, 7.1, fH -38.1 mm. The estimated value of the calculated deflection under loading was {tn + „o („ nn А462 1р. and - -2 - I 2 t (llZ .1) - (llZ.ll 33.6 mm. As follows from the data given, the difference in deflections under loading (-38.1) - (- 33.6) -4.5 mm is inverse to the sign of the difference between the initial deflections (-25, 3) - (- 27.9) -2.6 mm and exceeds its absolute value.The residual parameters of the right section after unloading were tocT 453 mm, oCotT (, 2, о 30.3 mm. Residual design deflection 1p, .Ch. "3 ± / 2 - - 3, 2 4 2 lll5A2) + () 30.2 mm. Due to the small difference between the actual and calculated residual deflections (O, 1 mm), the first operation was no longer repeated. The second operation (elimination of curvature) was carried out by a pure bend by loading the workpiece with two equal forces of Kos and mutually opposite direction until the parameters reached the following values: n 460.9 mm, n n-3.4, f "- 6.9 mm. After unloading, the indicated parameters 1 took the values: fost 461.1 mm, osg jbocT 0, FOCT -0.2 mm. The proposed method contributes to improving the performance and quality of edits.

Claims (2)

1. METHOD FOR PREPARING THE BILLETS, including eliminating the curvature of the straightened section of the workpiece by bending by applying two oppositely directed pairs of forces to the boundary sections of the section, characterized in that, with the aim of increasing productivity and accuracy of the dressing, before eliminating the curvature, it is preliminarily uniformly distributed along the length of the section. workpieces by means of local bending of the middle part of the straightened section — by two oppositely directed forces applied to the boundary sections of this section. 2. The method of pop. 1, characterized in that before eliminating the curvature, the difference between the actual and calculated deflections in the middle of the straightened section is determined, and in the process of uniform distribution of curvature along the length of the workpiece section, the deflection difference is reduced to zero, after which the difference in sign of these deflections is created increasing it from zero to a value determined by the initial difference of the mentioned deflections and the elastic properties of the workpiece, while the calculated deflection is determined from the relation where t and Y are, respectively the distance and the angle between the boundary portion of the workpiece straightens sections.